[PATCH -mm1 0/2] Fix unlocked call to idr_find()

[PATCH -mm1 0/2] Fix unlocked call to idr_find()

[Nadia.Derbey]

This a series of 2 patches that should be applied on top of the other ipc
patches, in 2.6.23-rc6-mm1.

The first one is an answer to the following issue pointed out by Jarek:

> Jarek Poplawski wrote:
> 1. ipc_lock() and ipc_lock_check() are used without ipc_ids.mutex,
> but it's probably wrong: they call idr_find() with ipc_ids pointer
> which needs this mutex, just like in similar code in: ipc_findkey(),
> ipc_get_maxid() or sysvipc_find_ipc().

The second one is a trivial patch that removes an unneeded parameter for
2 routines.

They should be applied to 2.6.23-rc6-mm1, in the following order:

[PATCH 1/2]: ipc_fix_idr_find_locking.patch
[PATCH 2/2]: ipc_remove_unneeded_params.patch


Regards,
Nadia

--

[PATCH -mm1 1/2] fixing idr_find() locking

[Nadia.Derbey]

[-- Attachment #1: ipc_fix_idr_find_locking.patch --]
[-- Type: text/plain, Size: 23464 bytes --]

[PATCH 01/02]


This is a patch that fixes the way idr_find() used to be called in ipc_lock():
in all the paths that don't imply an update of the ipcs idr, it was called
without the idr tree being locked.

The changes are:
  . in ipc_ids, the mutex has been changed into a reader/writer semaphore.
  . ipc_lock() now takes the mutex as a reader during the idr_find().
  . a new routine ipc_lock_down() has been defined: it doesn't take the
    mutex, assuming that it is being held by the caller. This is the routine
    that is now called in all the update paths.


Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>

---

This patch applies on top of the 2.6.23-rc6-mm1


 ipc/msg.c  |   41 ++++++++++++++++++++++----------
 ipc/sem.c  |   44 +++++++++++++++++++++++-----------
 ipc/shm.c  |   77 +++++++++++++++++++++++++++++++++++++++---------------------
 ipc/util.c |   78 ++++++++++++++++++++++++++++++++++++++++++++++++-------------
 ipc/util.h |   28 ++++++++++++++++++++-
 5 files changed, 198 insertions(+), 70 deletions(-)

Index: linux-2.6.23-rc6-mm1/ipc/util.h
===================================================================
--- linux-2.6.23-rc6-mm1.orig/ipc/util.h	2007-09-25 12:38:17.000000000 +0200
+++ linux-2.6.23-rc6-mm1/ipc/util.h	2007-09-27 10:13:18.000000000 +0200
@@ -32,7 +32,7 @@ struct ipc_ids {
 	int in_use;
 	unsigned short seq;
 	unsigned short seq_max;
-	struct mutex mutex;
+	struct rw_semaphore rw_mutex;
 	struct idr ipcs_idr;
 };
 
@@ -81,8 +81,10 @@ void __init ipc_init_proc_interface(cons
 
 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
 
-/* must be called with ids->mutex acquired.*/
+/* must be called with ids->rw_mutex acquired for writing */
 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
+
+/* must be called with ids->rw_mutex acquired for reading */
 int ipc_get_maxid(struct ipc_ids *);
 
 /* must be called with both locks acquired. */
@@ -107,6 +109,11 @@ void* ipc_rcu_alloc(int size);
 void ipc_rcu_getref(void *ptr);
 void ipc_rcu_putref(void *ptr);
 
+/*
+ * ipc_lock_down: called with rw_mutex held
+ * ipc_lock: called without that lock held
+ */
+struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 
 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
@@ -155,6 +162,23 @@ static inline void ipc_unlock(struct ker
 	rcu_read_unlock();
 }
 
+static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids,
+						int id)
+{
+	struct kern_ipc_perm *out;
+
+	out = ipc_lock_down(ids, id);
+	if (IS_ERR(out))
+		return out;
+
+	if (ipc_checkid(ids, out, id)) {
+		ipc_unlock(out);
+		return ERR_PTR(-EIDRM);
+	}
+
+	return out;
+}
+
 static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
 						int id)
 {
Index: linux-2.6.23-rc6-mm1/ipc/util.c
===================================================================
--- linux-2.6.23-rc6-mm1.orig/ipc/util.c	2007-09-21 10:32:03.000000000 +0200
+++ linux-2.6.23-rc6-mm1/ipc/util.c	2007-09-27 14:37:55.000000000 +0200
@@ -32,6 +32,7 @@
 #include <linux/proc_fs.h>
 #include <linux/audit.h>
 #include <linux/nsproxy.h>
+#include <linux/rwsem.h>
 
 #include <asm/unistd.h>
 
@@ -136,7 +137,7 @@ __initcall(ipc_init);
  
 void ipc_init_ids(struct ipc_ids *ids)
 {
-	mutex_init(&ids->mutex);
+	init_rwsem(&ids->rw_mutex);
 
 	ids->in_use = 0;
 	ids->seq = 0;
@@ -191,7 +192,7 @@ void __init ipc_init_proc_interface(cons
  *	@ids: Identifier set
  *	@key: The key to find
  *	
- *	Requires ipc_ids.mutex locked.
+ *	Requires ipc_ids.rw_mutex locked.
  *	Returns the LOCKED pointer to the ipc structure if found or NULL
  *	if not.
  *	If key is found ipc points to the owning ipc structure
@@ -225,7 +226,7 @@ static struct kern_ipc_perm *ipc_findkey
  *	ipc_get_maxid 	-	get the last assigned id
  *	@ids: IPC identifier set
  *
- *	Called with ipc_ids.mutex held.
+ *	Called with ipc_ids.rw_mutex held.
  */
 
 int ipc_get_maxid(struct ipc_ids *ids)
@@ -263,7 +264,7 @@ int ipc_get_maxid(struct ipc_ids *ids)
  *	is returned. The 'new' entry is returned in a locked state on success.
  *	On failure the entry is not locked and -1 is returned.
  *
- *	Called with ipc_ids.mutex held.
+ *	Called with ipc_ids.rw_mutex held as a writer.
  */
  
 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
@@ -316,9 +317,9 @@ int ipcget_new(struct ipc_namespace *ns,
 	if (!err)
 		return -ENOMEM;
 
-	mutex_lock(&ids->mutex);
+	down_write(&ids->rw_mutex);
 	err = ops->getnew(ns, params);
-	mutex_unlock(&ids->mutex);
+	up_write(&ids->rw_mutex);
 
 	return err;
 }
@@ -335,7 +336,7 @@ int ipcget_new(struct ipc_namespace *ns,
  *
  *	On success, the IPC id is returned.
  *
- *	It is called with ipc_ids.mutex and ipcp->lock held.
+ *	It is called with ipc_ids.rw_mutex and ipcp->lock held.
  */
 static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
 			struct ipc_params *params)
@@ -376,7 +377,11 @@ int ipcget_public(struct ipc_namespace *
 
 	err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
 
-	mutex_lock(&ids->mutex);
+	/*
+	 * Take the lock as a writer since we are potentially going to add
+	 * a new entry + read locks are not "upgradable"
+	 */
+	down_write(&ids->rw_mutex);
 	ipcp = ipc_findkey(ids, params->key);
 	if (ipcp == NULL) {
 		/* key not used */
@@ -404,7 +409,7 @@ int ipcget_public(struct ipc_namespace *
 		}
 		ipc_unlock(ipcp);
 	}
-	mutex_unlock(&ids->mutex);
+	up_write(&ids->rw_mutex);
 
 	return err;
 }
@@ -415,8 +420,8 @@ int ipcget_public(struct ipc_namespace *
  *	@ids: IPC identifier set
  *	@ipcp: ipc perm structure containing the identifier to remove
  *
- *	ipc_ids.mutex and the spinlock for this ID are held before this
- *	function is called, and remain locked on the exit.
+ *	ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
+ *	before this function is called, and remain locked on the exit.
  */
  
 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
@@ -680,15 +685,17 @@ void ipc64_perm_to_ipc_perm (struct ipc6
 }
 
 /**
- * ipc_lock - Lock an ipc structure
+ * ipc_lock - Lock an ipc structure without rw_mutex held
  * @ids: IPC identifier set
  * @id: ipc id to look for
  *
  * Look for an id in the ipc ids idr and lock the associated ipc object.
  *
- * ipc_ids.mutex is not necessarily held before this function is called,
- * that's why we enter a RCU read section.
  * The ipc object is locked on exit.
+ *
+ * This is the routine that should be called when the rw_mutex is not already
+ * held, i.e. idr tree not protected: it protects the idr tree in read mode
+ * during the idr_find().
  */
 
 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
@@ -696,13 +703,18 @@ struct kern_ipc_perm *ipc_lock(struct ip
 	struct kern_ipc_perm *out;
 	int lid = ipcid_to_idx(id);
 
+	down_read(&ids->rw_mutex);
+
 	rcu_read_lock();
 	out = idr_find(&ids->ipcs_idr, lid);
 	if (out == NULL) {
 		rcu_read_unlock();
+		up_read(&ids->rw_mutex);
 		return ERR_PTR(-EINVAL);
 	}
 
+	up_read(&ids->rw_mutex);
+
 	spin_lock(&out->lock);
 	
 	/* ipc_rmid() may have already freed the ID while ipc_lock
@@ -717,6 +729,40 @@ struct kern_ipc_perm *ipc_lock(struct ip
 	return out;
 }
 
+/**
+ * ipc_lock_down - Lock an ipc structure with rw_sem held
+ * @ids: IPC identifier set
+ * @id: ipc id to look for
+ *
+ * Look for an id in the ipc ids idr and lock the associated ipc object.
+ *
+ * The ipc object is locked on exit.
+ *
+ * This is the routine that should be called when the rw_mutex is already
+ * held, i.e. idr tree protected.
+ */
+
+struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *ids, int id)
+{
+	struct kern_ipc_perm *out;
+	int lid = ipcid_to_idx(id);
+
+	rcu_read_lock();
+	out = idr_find(&ids->ipcs_idr, lid);
+	if (out == NULL) {
+		rcu_read_unlock();
+		return ERR_PTR(-EINVAL);
+	}
+
+	spin_lock(&out->lock);
+
+	/*
+	 * No need to verify that the structure is still valid since the
+	 * rw_mutex is held.
+	 */
+	return out;
+}
+
 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
 
 
@@ -808,7 +854,7 @@ static void *sysvipc_proc_start(struct s
 	 * Take the lock - this will be released by the corresponding
 	 * call to stop().
 	 */
-	mutex_lock(&ids->mutex);
+	down_read(&ids->rw_mutex);
 
 	/* pos < 0 is invalid */
 	if (*pos < 0)
@@ -835,7 +881,7 @@ static void sysvipc_proc_stop(struct seq
 
 	ids = iter->ns->ids[iface->ids];
 	/* Release the lock we took in start() */
-	mutex_unlock(&ids->mutex);
+	up_read(&ids->rw_mutex);
 }
 
 static int sysvipc_proc_show(struct seq_file *s, void *it)
Index: linux-2.6.23-rc6-mm1/ipc/msg.c
===================================================================
--- linux-2.6.23-rc6-mm1.orig/ipc/msg.c	2007-09-21 10:33:08.000000000 +0200
+++ linux-2.6.23-rc6-mm1/ipc/msg.c	2007-09-27 10:34:25.000000000 +0200
@@ -34,7 +34,7 @@
 #include <linux/syscalls.h>
 #include <linux/audit.h>
 #include <linux/seq_file.h>
-#include <linux/mutex.h>
+#include <linux/rwsem.h>
 #include <linux/nsproxy.h>
 
 #include <asm/current.h>
@@ -110,7 +110,7 @@ void msg_exit_ns(struct ipc_namespace *n
 	int next_id;
 	int total, in_use;
 
-	mutex_lock(&msg_ids(ns).mutex);
+	down_write(&msg_ids(ns).rw_mutex);
 
 	in_use = msg_ids(ns).in_use;
 
@@ -122,7 +122,8 @@ void msg_exit_ns(struct ipc_namespace *n
 		freeque(ns, msq);
 		total++;
 	}
-	mutex_unlock(&msg_ids(ns).mutex);
+
+	up_write(&msg_ids(ns).rw_mutex);
 
 	kfree(ns->ids[IPC_MSG_IDS]);
 	ns->ids[IPC_MSG_IDS] = NULL;
@@ -136,6 +137,22 @@ void __init msg_init(void)
 				IPC_MSG_IDS, sysvipc_msg_proc_show);
 }
 
+/*
+ * This routine is called in the paths where the rw_mutex is held to protect
+ * access to the idr tree.
+ */
+static inline struct msg_queue *msg_lock_check_down(struct ipc_namespace *ns,
+						int id)
+{
+	struct kern_ipc_perm *ipcp = ipc_lock_check_down(&msg_ids(ns), id);
+
+	return container_of(ipcp, struct msg_queue, q_perm);
+}
+
+/*
+ * msg_lock_(check_) routines are called in the paths where the rw_mutex
+ * is not held.
+ */
 static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id)
 {
 	struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id);
@@ -161,7 +178,7 @@ static inline void msg_rmid(struct ipc_n
  * @ns: namespace
  * @params: ptr to the structure that contains the key and msgflg
  *
- * Called with msg_ids.mutex held
+ * Called with msg_ids.rw_mutex held (writer)
  */
 static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 {
@@ -260,8 +277,8 @@ static void expunge_all(struct msg_queue
  * removes the message queue from message queue ID IDR, and cleans up all the
  * messages associated with this queue.
  *
- * msg_ids.mutex and the spinlock for this message queue are held
- * before freeque() is called. msg_ids.mutex remains locked on exit.
+ * msg_ids.rw_mutex (writer) and the spinlock for this message queue are held
+ * before freeque() is called. msg_ids.rw_mutex remains locked on exit.
  */
 static void freeque(struct ipc_namespace *ns, struct msg_queue *msq)
 {
@@ -286,7 +303,7 @@ static void freeque(struct ipc_namespace
 }
 
 /*
- * Called with msg_ids.mutex and ipcp locked.
+ * Called with msg_ids.rw_mutex and ipcp locked.
  */
 static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
 {
@@ -444,7 +461,7 @@ asmlinkage long sys_msgctl(int msqid, in
 		msginfo.msgmnb = ns->msg_ctlmnb;
 		msginfo.msgssz = MSGSSZ;
 		msginfo.msgseg = MSGSEG;
-		mutex_lock(&msg_ids(ns).mutex);
+		down_read(&msg_ids(ns).rw_mutex);
 		if (cmd == MSG_INFO) {
 			msginfo.msgpool = msg_ids(ns).in_use;
 			msginfo.msgmap = atomic_read(&msg_hdrs);
@@ -455,7 +472,7 @@ asmlinkage long sys_msgctl(int msqid, in
 			msginfo.msgtql = MSGTQL;
 		}
 		max_id = ipc_get_maxid(&msg_ids(ns));
-		mutex_unlock(&msg_ids(ns).mutex);
+		up_read(&msg_ids(ns).rw_mutex);
 		if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
 			return -EFAULT;
 		return (max_id < 0) ? 0 : max_id;
@@ -516,8 +533,8 @@ asmlinkage long sys_msgctl(int msqid, in
 		return  -EINVAL;
 	}
 
-	mutex_lock(&msg_ids(ns).mutex);
-	msq = msg_lock_check(ns, msqid);
+	down_write(&msg_ids(ns).rw_mutex);
+	msq = msg_lock_check_down(ns, msqid);
 	if (IS_ERR(msq)) {
 		err = PTR_ERR(msq);
 		goto out_up;
@@ -576,7 +593,7 @@ asmlinkage long sys_msgctl(int msqid, in
 	}
 	err = 0;
 out_up:
-	mutex_unlock(&msg_ids(ns).mutex);
+	up_write(&msg_ids(ns).rw_mutex);
 	return err;
 out_unlock_up:
 	msg_unlock(msq);
Index: linux-2.6.23-rc6-mm1/ipc/sem.c
===================================================================
--- linux-2.6.23-rc6-mm1.orig/ipc/sem.c	2007-09-21 10:33:50.000000000 +0200
+++ linux-2.6.23-rc6-mm1/ipc/sem.c	2007-09-27 10:35:40.000000000 +0200
@@ -80,7 +80,7 @@
 #include <linux/audit.h>
 #include <linux/capability.h>
 #include <linux/seq_file.h>
-#include <linux/mutex.h>
+#include <linux/rwsem.h>
 #include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
@@ -148,7 +148,7 @@ void sem_exit_ns(struct ipc_namespace *n
 	int next_id;
 	int total, in_use;
 
-	mutex_lock(&sem_ids(ns).mutex);
+	down_write(&sem_ids(ns).rw_mutex);
 
 	in_use = sem_ids(ns).in_use;
 
@@ -160,7 +160,7 @@ void sem_exit_ns(struct ipc_namespace *n
 		freeary(ns, sma);
 		total++;
 	}
-	mutex_unlock(&sem_ids(ns).mutex);
+	up_write(&sem_ids(ns).rw_mutex);
 
 	kfree(ns->ids[IPC_SEM_IDS]);
 	ns->ids[IPC_SEM_IDS] = NULL;
@@ -174,6 +174,22 @@ void __init sem_init (void)
 				IPC_SEM_IDS, sysvipc_sem_proc_show);
 }
 
+/*
+ * This routine is called in the paths where the rw_mutex is held to protect
+ * access to the idr tree.
+ */
+static inline struct sem_array *sem_lock_check_down(struct ipc_namespace *ns,
+						int id)
+{
+	struct kern_ipc_perm *ipcp = ipc_lock_check_down(&sem_ids(ns), id);
+
+	return container_of(ipcp, struct sem_array, sem_perm);
+}
+
+/*
+ * sem_lock_(check_) routines are called in the paths where the rw_mutex
+ * is not held.
+ */
 static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)
 {
 	struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id);
@@ -233,7 +249,7 @@ static inline void sem_rmid(struct ipc_n
  * @ns: namespace
  * @params: ptr to the structure that contains key, semflg and nsems
  *
- * Called with sem_ids.mutex held
+ * Called with sem_ids.rw_mutex held (as a writer)
  */
 
 static int newary(struct ipc_namespace *ns, struct ipc_params *params)
@@ -290,7 +306,7 @@ static int newary(struct ipc_namespace *
 
 
 /*
- * Called with sem_ids.mutex and ipcp locked.
+ * Called with sem_ids.rw_mutex and ipcp locked.
  */
 static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
 {
@@ -301,7 +317,7 @@ static inline int sem_security(struct ke
 }
 
 /*
- * Called with sem_ids.mutex and ipcp locked.
+ * Called with sem_ids.rw_mutex and ipcp locked.
  */
 static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
 				struct ipc_params *params)
@@ -528,9 +544,9 @@ static int count_semzcnt (struct sem_arr
 	return semzcnt;
 }
 
-/* Free a semaphore set. freeary() is called with sem_ids.mutex locked and
- * the spinlock for this semaphore set hold. sem_ids.mutex remains locked
- * on exit.
+/* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked
+ * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex
+ * remains locked on exit.
  */
 static void freeary(struct ipc_namespace *ns, struct sem_array *sma)
 {
@@ -615,7 +631,7 @@ static int semctl_nolock(struct ipc_name
 		seminfo.semmnu = SEMMNU;
 		seminfo.semmap = SEMMAP;
 		seminfo.semume = SEMUME;
-		mutex_lock(&sem_ids(ns).mutex);
+		down_read(&sem_ids(ns).rw_mutex);
 		if (cmd == SEM_INFO) {
 			seminfo.semusz = sem_ids(ns).in_use;
 			seminfo.semaem = ns->used_sems;
@@ -624,7 +640,7 @@ static int semctl_nolock(struct ipc_name
 			seminfo.semaem = SEMAEM;
 		}
 		max_id = ipc_get_maxid(&sem_ids(ns));
-		mutex_unlock(&sem_ids(ns).mutex);
+		up_read(&sem_ids(ns).rw_mutex);
 		if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo))) 
 			return -EFAULT;
 		return (max_id < 0) ? 0: max_id;
@@ -895,7 +911,7 @@ static int semctl_down(struct ipc_namesp
 		if(copy_semid_from_user (&setbuf, arg.buf, version))
 			return -EFAULT;
 	}
-	sma = sem_lock_check(ns, semid);
+	sma = sem_lock_check_down(ns, semid);
 	if (IS_ERR(sma))
 		return PTR_ERR(sma);
 
@@ -976,9 +992,9 @@ asmlinkage long sys_semctl (int semid, i
 		return err;
 	case IPC_RMID:
 	case IPC_SET:
-		mutex_lock(&sem_ids(ns).mutex);
+		down_write(&sem_ids(ns).rw_mutex);
 		err = semctl_down(ns,semid,semnum,cmd,version,arg);
-		mutex_unlock(&sem_ids(ns).mutex);
+		up_write(&sem_ids(ns).rw_mutex);
 		return err;
 	default:
 		return -EINVAL;
Index: linux-2.6.23-rc6-mm1/ipc/shm.c
===================================================================
--- linux-2.6.23-rc6-mm1.orig/ipc/shm.c	2007-09-21 10:34:25.000000000 +0200
+++ linux-2.6.23-rc6-mm1/ipc/shm.c	2007-09-27 10:30:30.000000000 +0200
@@ -35,7 +35,7 @@
 #include <linux/capability.h>
 #include <linux/ptrace.h>
 #include <linux/seq_file.h>
-#include <linux/mutex.h>
+#include <linux/rwsem.h>
 #include <linux/nsproxy.h>
 #include <linux/mount.h>
 
@@ -83,8 +83,8 @@ static void __shm_init_ns(struct ipc_nam
 }
 
 /*
- * Called with shm_ids.mutex and the shp structure locked.
- * Only shm_ids.mutex remains locked on exit.
+ * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
+ * Only shm_ids.rw_mutex remains locked on exit.
  */
 static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
 {
@@ -115,7 +115,7 @@ void shm_exit_ns(struct ipc_namespace *n
 	int next_id;
 	int total, in_use;
 
-	mutex_lock(&shm_ids(ns).mutex);
+	down_write(&shm_ids(ns).rw_mutex);
 
 	in_use = shm_ids(ns).in_use;
 
@@ -127,7 +127,7 @@ void shm_exit_ns(struct ipc_namespace *n
 		do_shm_rmid(ns, shp);
 		total++;
 	}
-	mutex_unlock(&shm_ids(ns).mutex);
+	up_write(&shm_ids(ns).rw_mutex);
 
 	kfree(ns->ids[IPC_SHM_IDS]);
 	ns->ids[IPC_SHM_IDS] = NULL;
@@ -141,6 +141,31 @@ void __init shm_init (void)
 				IPC_SHM_IDS, sysvipc_shm_proc_show);
 }
 
+/*
+ * shm_lock_(check_)down routines are called in the paths where the rw_mutex
+ * is held to protect access to the idr tree.
+ */
+static inline struct shmid_kernel *shm_lock_down(struct ipc_namespace *ns,
+						int id)
+{
+	struct kern_ipc_perm *ipcp = ipc_lock_down(&shm_ids(ns), id);
+
+	return container_of(ipcp, struct shmid_kernel, shm_perm);
+}
+
+static inline struct shmid_kernel *shm_lock_check_down(
+						struct ipc_namespace *ns,
+						int id)
+{
+	struct kern_ipc_perm *ipcp = ipc_lock_check_down(&shm_ids(ns), id);
+
+	return container_of(ipcp, struct shmid_kernel, shm_perm);
+}
+
+/*
+ * shm_lock_(check_) routines are called in the paths where the rw_mutex
+ * is not held.
+ */
 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 {
 	struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
@@ -189,7 +214,7 @@ static void shm_open(struct vm_area_stru
  * @ns: namespace
  * @shp: struct to free
  *
- * It has to be called with shp and shm_ids.mutex locked,
+ * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
  * but returns with shp unlocked and freed.
  */
 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
@@ -220,9 +245,9 @@ static void shm_close(struct vm_area_str
 	struct shmid_kernel *shp;
 	struct ipc_namespace *ns = sfd->ns;
 
-	mutex_lock(&shm_ids(ns).mutex);
+	down_write(&shm_ids(ns).rw_mutex);
 	/* remove from the list of attaches of the shm segment */
-	shp = shm_lock(ns, sfd->id);
+	shp = shm_lock_down(ns, sfd->id);
 	BUG_ON(IS_ERR(shp));
 	shp->shm_lprid = task_tgid_vnr(current);
 	shp->shm_dtim = get_seconds();
@@ -232,7 +257,7 @@ static void shm_close(struct vm_area_str
 		shm_destroy(ns, shp);
 	else
 		shm_unlock(shp);
-	mutex_unlock(&shm_ids(ns).mutex);
+	up_write(&shm_ids(ns).rw_mutex);
 }
 
 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
@@ -353,7 +378,7 @@ static struct vm_operations_struct shm_v
  * @ns: namespace
  * @params: ptr to the structure that contains key, size and shmflg
  *
- * Called with shm_ids.mutex held
+ * Called with shm_ids.rw_mutex held as a writer.
  */
 
 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
@@ -442,7 +467,7 @@ no_file:
 }
 
 /*
- * Called with shm_ids.mutex and ipcp locked.
+ * Called with shm_ids.rw_mutex and ipcp locked.
  */
 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 {
@@ -453,7 +478,7 @@ static inline int shm_security(struct ke
 }
 
 /*
- * Called with shm_ids.mutex and ipcp locked.
+ * Called with shm_ids.rw_mutex and ipcp locked.
  */
 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 				struct ipc_params *params)
@@ -578,7 +603,7 @@ static inline unsigned long copy_shminfo
 }
 
 /*
- * Called with shm_ids.mutex held
+ * Called with shm_ids.rw_mutex held as a reader
  */
 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 		unsigned long *swp)
@@ -649,9 +674,9 @@ asmlinkage long sys_shmctl (int shmid, i
 		if(copy_shminfo_to_user (buf, &shminfo, version))
 			return -EFAULT;
 
-		mutex_lock(&shm_ids(ns).mutex);
+		down_read(&shm_ids(ns).rw_mutex);
 		err = ipc_get_maxid(&shm_ids(ns));
-		mutex_unlock(&shm_ids(ns).mutex);
+		up_read(&shm_ids(ns).rw_mutex);
 
 		if(err<0)
 			err = 0;
@@ -666,14 +691,14 @@ asmlinkage long sys_shmctl (int shmid, i
 			return err;
 
 		memset(&shm_info,0,sizeof(shm_info));
-		mutex_lock(&shm_ids(ns).mutex);
+		down_read(&shm_ids(ns).rw_mutex);
 		shm_info.used_ids = shm_ids(ns).in_use;
 		shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
 		shm_info.shm_tot = ns->shm_tot;
 		shm_info.swap_attempts = 0;
 		shm_info.swap_successes = 0;
 		err = ipc_get_maxid(&shm_ids(ns));
-		mutex_unlock(&shm_ids(ns).mutex);
+		up_read(&shm_ids(ns).rw_mutex);
 		if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
 			err = -EFAULT;
 			goto out;
@@ -786,8 +811,8 @@ asmlinkage long sys_shmctl (int shmid, i
 		 *	Instead we set a destroyed flag, and then blow
 		 *	the name away when the usage hits zero.
 		 */
-		mutex_lock(&shm_ids(ns).mutex);
-		shp = shm_lock_check(ns, shmid);
+		down_write(&shm_ids(ns).rw_mutex);
+		shp = shm_lock_check_down(ns, shmid);
 		if (IS_ERR(shp)) {
 			err = PTR_ERR(shp);
 			goto out_up;
@@ -809,7 +834,7 @@ asmlinkage long sys_shmctl (int shmid, i
 			goto out_unlock_up;
 
 		do_shm_rmid(ns, shp);
-		mutex_unlock(&shm_ids(ns).mutex);
+		up_write(&shm_ids(ns).rw_mutex);
 		goto out;
 	}
 
@@ -824,8 +849,8 @@ asmlinkage long sys_shmctl (int shmid, i
 			err = -EFAULT;
 			goto out;
 		}
-		mutex_lock(&shm_ids(ns).mutex);
-		shp = shm_lock_check(ns, shmid);
+		down_write(&shm_ids(ns).rw_mutex);
+		shp = shm_lock_check_down(ns, shmid);
 		if (IS_ERR(shp)) {
 			err = PTR_ERR(shp);
 			goto out_up;
@@ -864,7 +889,7 @@ asmlinkage long sys_shmctl (int shmid, i
 out_unlock_up:
 	shm_unlock(shp);
 out_up:
-	mutex_unlock(&shm_ids(ns).mutex);
+	up_write(&shm_ids(ns).rw_mutex);
 	goto out;
 out_unlock:
 	shm_unlock(shp);
@@ -1000,8 +1025,8 @@ invalid:
 	fput(file);
 
 out_nattch:
-	mutex_lock(&shm_ids(ns).mutex);
-	shp = shm_lock(ns, shmid);
+	down_write(&shm_ids(ns).rw_mutex);
+	shp = shm_lock_down(ns, shmid);
 	BUG_ON(IS_ERR(shp));
 	shp->shm_nattch--;
 	if(shp->shm_nattch == 0 &&
@@ -1009,7 +1034,7 @@ out_nattch:
 		shm_destroy(ns, shp);
 	else
 		shm_unlock(shp);
-	mutex_unlock(&shm_ids(ns).mutex);
+	up_write(&shm_ids(ns).rw_mutex);
 
 out:
 	return err;

--

[PATCH -mm1 2/2] Removing unneeded parameters

[Nadia.Derbey]

[-- Attachment #1: ipc_remove_unneeded_params.patch --]
[-- Type: text/plain, Size: 4987 bytes --]

[PATCH 02/02]


This is a trivial patch that removes the unneeded parameters from
ipc_checkid() and ipc_buildid() interfaces.


Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>

---

This patch applies on top of the 2.6.23-rc6-mm1


 ipc/msg.c  |    5 ++---
 ipc/sem.c  |   10 ++++------
 ipc/shm.c  |    5 ++---
 ipc/util.h |    9 ++++-----
 4 files changed, 12 insertions(+), 17 deletions(-)

Index: linux-2.6.23-rc6-mm1/ipc/util.h
===================================================================
--- linux-2.6.23-rc6-mm1.orig/ipc/util.h	2007-09-27 10:13:18.000000000 +0200
+++ linux-2.6.23-rc6-mm1/ipc/util.h	2007-09-27 15:09:51.000000000 +0200
@@ -134,7 +134,7 @@ extern int ipcget_new(struct ipc_namespa
 extern int ipcget_public(struct ipc_namespace *, struct ipc_ids *,
 			struct ipc_ops *, struct ipc_params *);
 
-static inline int ipc_buildid(struct ipc_ids *ids, int id, int seq)
+static inline int ipc_buildid(int id, int seq)
 {
 	return SEQ_MULTIPLIER * seq + id;
 }
@@ -142,8 +142,7 @@ static inline int ipc_buildid(struct ipc
 /*
  * Must be called with ipcp locked
  */
-static inline int ipc_checkid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp,
-				int uid)
+static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 {
 	if (uid / SEQ_MULTIPLIER != ipcp->seq)
 		return 1;
@@ -171,7 +170,7 @@ static inline struct kern_ipc_perm *ipc_
 	if (IS_ERR(out))
 		return out;
 
-	if (ipc_checkid(ids, out, id)) {
+	if (ipc_checkid(out, id)) {
 		ipc_unlock(out);
 		return ERR_PTR(-EIDRM);
 	}
@@ -188,7 +187,7 @@ static inline struct kern_ipc_perm *ipc_
 	if (IS_ERR(out))
 		return out;
 
-	if (ipc_checkid(ids, out, id)) {
+	if (ipc_checkid(out, id)) {
 		ipc_unlock(out);
 		return ERR_PTR(-EIDRM);
 	}
Index: linux-2.6.23-rc6-mm1/ipc/msg.c
===================================================================
--- linux-2.6.23-rc6-mm1.orig/ipc/msg.c	2007-09-27 10:34:25.000000000 +0200
+++ linux-2.6.23-rc6-mm1/ipc/msg.c	2007-09-27 15:03:26.000000000 +0200
@@ -74,8 +74,7 @@ static struct ipc_ids init_msg_ids;
 #define msg_ids(ns)	(*((ns)->ids[IPC_MSG_IDS]))
 
 #define msg_unlock(msq)		ipc_unlock(&(msq)->q_perm)
-#define msg_buildid(ns, id, seq) \
-	ipc_buildid(&msg_ids(ns), id, seq)
+#define msg_buildid(id, seq)	ipc_buildid(id, seq)
 
 static void freeque(struct ipc_namespace *, struct msg_queue *);
 static int newque(struct ipc_namespace *, struct ipc_params *);
@@ -211,7 +210,7 @@ static int newque(struct ipc_namespace *
 		return -ENOSPC;
 	}
 
-	msq->q_perm.id = msg_buildid(ns, id, msq->q_perm.seq);
+	msq->q_perm.id = msg_buildid(id, msq->q_perm.seq);
 	msq->q_stime = msq->q_rtime = 0;
 	msq->q_ctime = get_seconds();
 	msq->q_cbytes = msq->q_qnum = 0;
Index: linux-2.6.23-rc6-mm1/ipc/sem.c
===================================================================
--- linux-2.6.23-rc6-mm1.orig/ipc/sem.c	2007-09-27 10:35:40.000000000 +0200
+++ linux-2.6.23-rc6-mm1/ipc/sem.c	2007-09-27 15:10:48.000000000 +0200
@@ -89,10 +89,8 @@
 #define sem_ids(ns)	(*((ns)->ids[IPC_SEM_IDS]))
 
 #define sem_unlock(sma)		ipc_unlock(&(sma)->sem_perm)
-#define sem_checkid(ns, sma, semid)	\
-	ipc_checkid(&sem_ids(ns),&sma->sem_perm,semid)
-#define sem_buildid(ns, id, seq) \
-	ipc_buildid(&sem_ids(ns), id, seq)
+#define sem_checkid(sma, semid)	ipc_checkid(&sma->sem_perm, semid)
+#define sem_buildid(id, seq)	ipc_buildid(id, seq)
 
 static struct ipc_ids init_sem_ids;
 
@@ -292,7 +290,7 @@ static int newary(struct ipc_namespace *
 	}
 	ns->used_sems += nsems;
 
-	sma->sem_perm.id = sem_buildid(ns, id, sma->sem_perm.seq);
+	sma->sem_perm.id = sem_buildid(id, sma->sem_perm.seq);
 	sma->sem_base = (struct sem *) &sma[1];
 	/* sma->sem_pending = NULL; */
 	sma->sem_pending_last = &sma->sem_pending;
@@ -1386,7 +1384,7 @@ void exit_sem(struct task_struct *tsk)
 		if (u->semid == -1)
 			goto next_entry;
 
-		BUG_ON(sem_checkid(ns,sma,u->semid));
+		BUG_ON(sem_checkid(sma, u->semid));
 
 		/* remove u from the sma->undo list */
 		for (unp = &sma->undo; (un = *unp); unp = &un->id_next) {
Index: linux-2.6.23-rc6-mm1/ipc/shm.c
===================================================================
--- linux-2.6.23-rc6-mm1.orig/ipc/shm.c	2007-09-27 10:30:30.000000000 +0200
+++ linux-2.6.23-rc6-mm1/ipc/shm.c	2007-09-27 15:08:41.000000000 +0200
@@ -61,8 +61,7 @@ static struct ipc_ids init_shm_ids;
 
 #define shm_unlock(shp)			\
 	ipc_unlock(&(shp)->shm_perm)
-#define shm_buildid(ns, id, seq)	\
-	ipc_buildid(&shm_ids(ns), id, seq)
+#define shm_buildid(id, seq)	ipc_buildid(id, seq)
 
 static int newseg(struct ipc_namespace *, struct ipc_params *);
 static void shm_open(struct vm_area_struct *vma);
@@ -445,7 +444,7 @@ static int newseg(struct ipc_namespace *
 	shp->shm_ctim = get_seconds();
 	shp->shm_segsz = size;
 	shp->shm_nattch = 0;
-	shp->shm_perm.id = shm_buildid(ns, id, shp->shm_perm.seq);
+	shp->shm_perm.id = shm_buildid(id, shp->shm_perm.seq);
 	shp->shm_file = file;
 	/*
 	 * shmid gets reported as "inode#" in /proc/pid/maps.

--

Re: [PATCH -mm1 0/2] Fix unlocked call to idr_find()

[Jarek Poplawski]

On Thu, Sep 27, 2007 at 04:33:54PM +0200, Nadia.Derbey@bull.net wrote:
> 
> This a series of 2 patches that should be applied on top of the other ipc
> patches, in 2.6.23-rc6-mm1.
...
> They should be applied to 2.6.23-rc6-mm1, in the following order:

Didn't you mean 2.6.23-rc8-mm1, btw?

Regards,
Jarek P.

Re: [PATCH -mm1 0/2] Fix unlocked call to idr_find()

[Nadia Derbey]

Jarek Poplawski wrote:
> On Thu, Sep 27, 2007 at 04:33:54PM +0200, Nadia.Derbey@bull.net wrote:
> 
>>This a series of 2 patches that should be applied on top of the other ipc
>>patches, in 2.6.23-rc6-mm1.
> 
> ...
> 
>>They should be applied to 2.6.23-rc6-mm1, in the following order:
> 
> 
> Didn't you mean 2.6.23-rc8-mm1, btw?
> 
> Regards,
> Jarek P.
> 

No, what I wrote is exactly what I meant: unfortunately I couldn't get 
the rc8-mm1 yet.
But, Before building the patch, I applied the ipc patches that had been 
integrated in rc7-mm1.
Nothing happened in rc8-mm1.
So you should have no problem appying these patches to your rc8-mm1 tree.

Regards,
Nadia

Re: [PATCH -mm1 1/2] fixing idr_find() locking

[Jarek Poplawski]

On Thu, Sep 27, 2007 at 04:33:55PM +0200, Nadia.Derbey@bull.net wrote:
> [PATCH 01/02]
> 
> 
> This is a patch that fixes the way idr_find() used to be called in ipc_lock():
> in all the paths that don't imply an update of the ipcs idr, it was called
> without the idr tree being locked.
> 
> The changes are:
>   . in ipc_ids, the mutex has been changed into a reader/writer semaphore.
>   . ipc_lock() now takes the mutex as a reader during the idr_find().
>   . a new routine ipc_lock_down() has been defined: it doesn't take the
>     mutex, assuming that it is being held by the caller. This is the routine
>     that is now called in all the update paths.
> 
> 
> Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>

Acked-by: Jarek Poplawski <jarkao2@o2.pl>

PS: there is one big mistake around To/Cc ordering, so I doubt Andrew
will ever sign this...

> 
> ---
> 
> This patch applies on top of the 2.6.23-rc6-mm1
> 
> 
>  ipc/msg.c  |   41 ++++++++++++++++++++++----------
>  ipc/sem.c  |   44 +++++++++++++++++++++++-----------
>  ipc/shm.c  |   77 +++++++++++++++++++++++++++++++++++++++---------------------
>  ipc/util.c |   78 ++++++++++++++++++++++++++++++++++++++++++++++++-------------
>  ipc/util.h |   28 ++++++++++++++++++++-
>  5 files changed, 198 insertions(+), 70 deletions(-)
> 
> Index: linux-2.6.23-rc6-mm1/ipc/util.h
> ===================================================================
> --- linux-2.6.23-rc6-mm1.orig/ipc/util.h	2007-09-25 12:38:17.000000000 +0200
> +++ linux-2.6.23-rc6-mm1/ipc/util.h	2007-09-27 10:13:18.000000000 +0200
> @@ -32,7 +32,7 @@ struct ipc_ids {
>  	int in_use;
>  	unsigned short seq;
>  	unsigned short seq_max;
> -	struct mutex mutex;
> +	struct rw_semaphore rw_mutex;
>  	struct idr ipcs_idr;
>  };
>  
> @@ -81,8 +81,10 @@ void __init ipc_init_proc_interface(cons
>  
>  #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
>  
> -/* must be called with ids->mutex acquired.*/
> +/* must be called with ids->rw_mutex acquired for writing */
>  int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
> +
> +/* must be called with ids->rw_mutex acquired for reading */
>  int ipc_get_maxid(struct ipc_ids *);
>  
>  /* must be called with both locks acquired. */
> @@ -107,6 +109,11 @@ void* ipc_rcu_alloc(int size);
>  void ipc_rcu_getref(void *ptr);
>  void ipc_rcu_putref(void *ptr);
>  
> +/*
> + * ipc_lock_down: called with rw_mutex held
> + * ipc_lock: called without that lock held
> + */
> +struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
>  struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
>  
>  void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
> @@ -155,6 +162,23 @@ static inline void ipc_unlock(struct ker
>  	rcu_read_unlock();
>  }
>  
> +static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids,
> +						int id)
> +{
> +	struct kern_ipc_perm *out;
> +
> +	out = ipc_lock_down(ids, id);
> +	if (IS_ERR(out))
> +		return out;
> +
> +	if (ipc_checkid(ids, out, id)) {
> +		ipc_unlock(out);
> +		return ERR_PTR(-EIDRM);
> +	}
> +
> +	return out;
> +}
> +
>  static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
>  						int id)
>  {
> Index: linux-2.6.23-rc6-mm1/ipc/util.c
> ===================================================================
> --- linux-2.6.23-rc6-mm1.orig/ipc/util.c	2007-09-21 10:32:03.000000000 +0200
> +++ linux-2.6.23-rc6-mm1/ipc/util.c	2007-09-27 14:37:55.000000000 +0200
> @@ -32,6 +32,7 @@
>  #include <linux/proc_fs.h>
>  #include <linux/audit.h>
>  #include <linux/nsproxy.h>
> +#include <linux/rwsem.h>
>  
>  #include <asm/unistd.h>
>  
> @@ -136,7 +137,7 @@ __initcall(ipc_init);
>   
>  void ipc_init_ids(struct ipc_ids *ids)
>  {
> -	mutex_init(&ids->mutex);
> +	init_rwsem(&ids->rw_mutex);
>  
>  	ids->in_use = 0;
>  	ids->seq = 0;
> @@ -191,7 +192,7 @@ void __init ipc_init_proc_interface(cons
>   *	@ids: Identifier set
>   *	@key: The key to find
>   *	
> - *	Requires ipc_ids.mutex locked.
> + *	Requires ipc_ids.rw_mutex locked.
>   *	Returns the LOCKED pointer to the ipc structure if found or NULL
>   *	if not.
>   *	If key is found ipc points to the owning ipc structure
> @@ -225,7 +226,7 @@ static struct kern_ipc_perm *ipc_findkey
>   *	ipc_get_maxid 	-	get the last assigned id
>   *	@ids: IPC identifier set
>   *
> - *	Called with ipc_ids.mutex held.
> + *	Called with ipc_ids.rw_mutex held.
>   */
>  
>  int ipc_get_maxid(struct ipc_ids *ids)
> @@ -263,7 +264,7 @@ int ipc_get_maxid(struct ipc_ids *ids)
>   *	is returned. The 'new' entry is returned in a locked state on success.
>   *	On failure the entry is not locked and -1 is returned.
>   *
> - *	Called with ipc_ids.mutex held.
> + *	Called with ipc_ids.rw_mutex held as a writer.
>   */
>   
>  int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
> @@ -316,9 +317,9 @@ int ipcget_new(struct ipc_namespace *ns,
>  	if (!err)
>  		return -ENOMEM;
>  
> -	mutex_lock(&ids->mutex);
> +	down_write(&ids->rw_mutex);
>  	err = ops->getnew(ns, params);
> -	mutex_unlock(&ids->mutex);
> +	up_write(&ids->rw_mutex);
>  
>  	return err;
>  }
> @@ -335,7 +336,7 @@ int ipcget_new(struct ipc_namespace *ns,
>   *
>   *	On success, the IPC id is returned.
>   *
> - *	It is called with ipc_ids.mutex and ipcp->lock held.
> + *	It is called with ipc_ids.rw_mutex and ipcp->lock held.
>   */
>  static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
>  			struct ipc_params *params)
> @@ -376,7 +377,11 @@ int ipcget_public(struct ipc_namespace *
>  
>  	err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
>  
> -	mutex_lock(&ids->mutex);
> +	/*
> +	 * Take the lock as a writer since we are potentially going to add
> +	 * a new entry + read locks are not "upgradable"
> +	 */
> +	down_write(&ids->rw_mutex);
>  	ipcp = ipc_findkey(ids, params->key);
>  	if (ipcp == NULL) {
>  		/* key not used */
> @@ -404,7 +409,7 @@ int ipcget_public(struct ipc_namespace *
>  		}
>  		ipc_unlock(ipcp);
>  	}
> -	mutex_unlock(&ids->mutex);
> +	up_write(&ids->rw_mutex);
>  
>  	return err;
>  }
> @@ -415,8 +420,8 @@ int ipcget_public(struct ipc_namespace *
>   *	@ids: IPC identifier set
>   *	@ipcp: ipc perm structure containing the identifier to remove
>   *
> - *	ipc_ids.mutex and the spinlock for this ID are held before this
> - *	function is called, and remain locked on the exit.
> + *	ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
> + *	before this function is called, and remain locked on the exit.
>   */
>   
>  void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
> @@ -680,15 +685,17 @@ void ipc64_perm_to_ipc_perm (struct ipc6
>  }
>  
>  /**
> - * ipc_lock - Lock an ipc structure
> + * ipc_lock - Lock an ipc structure without rw_mutex held
>   * @ids: IPC identifier set
>   * @id: ipc id to look for
>   *
>   * Look for an id in the ipc ids idr and lock the associated ipc object.
>   *
> - * ipc_ids.mutex is not necessarily held before this function is called,
> - * that's why we enter a RCU read section.
>   * The ipc object is locked on exit.
> + *
> + * This is the routine that should be called when the rw_mutex is not already
> + * held, i.e. idr tree not protected: it protects the idr tree in read mode
> + * during the idr_find().
>   */
>  
>  struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
> @@ -696,13 +703,18 @@ struct kern_ipc_perm *ipc_lock(struct ip
>  	struct kern_ipc_perm *out;
>  	int lid = ipcid_to_idx(id);
>  
> +	down_read(&ids->rw_mutex);
> +
>  	rcu_read_lock();
>  	out = idr_find(&ids->ipcs_idr, lid);
>  	if (out == NULL) {
>  		rcu_read_unlock();
> +		up_read(&ids->rw_mutex);
>  		return ERR_PTR(-EINVAL);
>  	}
>  
> +	up_read(&ids->rw_mutex);
> +
>  	spin_lock(&out->lock);
>  	
>  	/* ipc_rmid() may have already freed the ID while ipc_lock
> @@ -717,6 +729,40 @@ struct kern_ipc_perm *ipc_lock(struct ip
>  	return out;
>  }
>  
> +/**
> + * ipc_lock_down - Lock an ipc structure with rw_sem held
> + * @ids: IPC identifier set
> + * @id: ipc id to look for
> + *
> + * Look for an id in the ipc ids idr and lock the associated ipc object.
> + *
> + * The ipc object is locked on exit.
> + *
> + * This is the routine that should be called when the rw_mutex is already
> + * held, i.e. idr tree protected.
> + */
> +
> +struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *ids, int id)
> +{
> +	struct kern_ipc_perm *out;
> +	int lid = ipcid_to_idx(id);
> +
> +	rcu_read_lock();
> +	out = idr_find(&ids->ipcs_idr, lid);
> +	if (out == NULL) {
> +		rcu_read_unlock();
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	spin_lock(&out->lock);
> +
> +	/*
> +	 * No need to verify that the structure is still valid since the
> +	 * rw_mutex is held.
> +	 */
> +	return out;
> +}
> +
>  #ifdef __ARCH_WANT_IPC_PARSE_VERSION
>  
>  
> @@ -808,7 +854,7 @@ static void *sysvipc_proc_start(struct s
>  	 * Take the lock - this will be released by the corresponding
>  	 * call to stop().
>  	 */
> -	mutex_lock(&ids->mutex);
> +	down_read(&ids->rw_mutex);
>  
>  	/* pos < 0 is invalid */
>  	if (*pos < 0)
> @@ -835,7 +881,7 @@ static void sysvipc_proc_stop(struct seq
>  
>  	ids = iter->ns->ids[iface->ids];
>  	/* Release the lock we took in start() */
> -	mutex_unlock(&ids->mutex);
> +	up_read(&ids->rw_mutex);
>  }
>  
>  static int sysvipc_proc_show(struct seq_file *s, void *it)
> Index: linux-2.6.23-rc6-mm1/ipc/msg.c
> ===================================================================
> --- linux-2.6.23-rc6-mm1.orig/ipc/msg.c	2007-09-21 10:33:08.000000000 +0200
> +++ linux-2.6.23-rc6-mm1/ipc/msg.c	2007-09-27 10:34:25.000000000 +0200
> @@ -34,7 +34,7 @@
>  #include <linux/syscalls.h>
>  #include <linux/audit.h>
>  #include <linux/seq_file.h>
> -#include <linux/mutex.h>
> +#include <linux/rwsem.h>
>  #include <linux/nsproxy.h>
>  
>  #include <asm/current.h>
> @@ -110,7 +110,7 @@ void msg_exit_ns(struct ipc_namespace *n
>  	int next_id;
>  	int total, in_use;
>  
> -	mutex_lock(&msg_ids(ns).mutex);
> +	down_write(&msg_ids(ns).rw_mutex);
>  
>  	in_use = msg_ids(ns).in_use;
>  
> @@ -122,7 +122,8 @@ void msg_exit_ns(struct ipc_namespace *n
>  		freeque(ns, msq);
>  		total++;
>  	}
> -	mutex_unlock(&msg_ids(ns).mutex);
> +
> +	up_write(&msg_ids(ns).rw_mutex);
>  
>  	kfree(ns->ids[IPC_MSG_IDS]);
>  	ns->ids[IPC_MSG_IDS] = NULL;
> @@ -136,6 +137,22 @@ void __init msg_init(void)
>  				IPC_MSG_IDS, sysvipc_msg_proc_show);
>  }
>  
> +/*
> + * This routine is called in the paths where the rw_mutex is held to protect
> + * access to the idr tree.
> + */
> +static inline struct msg_queue *msg_lock_check_down(struct ipc_namespace *ns,
> +						int id)
> +{
> +	struct kern_ipc_perm *ipcp = ipc_lock_check_down(&msg_ids(ns), id);
> +
> +	return container_of(ipcp, struct msg_queue, q_perm);
> +}
> +
> +/*
> + * msg_lock_(check_) routines are called in the paths where the rw_mutex
> + * is not held.
> + */
>  static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id)
>  {
>  	struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id);
> @@ -161,7 +178,7 @@ static inline void msg_rmid(struct ipc_n
>   * @ns: namespace
>   * @params: ptr to the structure that contains the key and msgflg
>   *
> - * Called with msg_ids.mutex held
> + * Called with msg_ids.rw_mutex held (writer)
>   */
>  static int newque(struct ipc_namespace *ns, struct ipc_params *params)
>  {
> @@ -260,8 +277,8 @@ static void expunge_all(struct msg_queue
>   * removes the message queue from message queue ID IDR, and cleans up all the
>   * messages associated with this queue.
>   *
> - * msg_ids.mutex and the spinlock for this message queue are held
> - * before freeque() is called. msg_ids.mutex remains locked on exit.
> + * msg_ids.rw_mutex (writer) and the spinlock for this message queue are held
> + * before freeque() is called. msg_ids.rw_mutex remains locked on exit.
>   */
>  static void freeque(struct ipc_namespace *ns, struct msg_queue *msq)
>  {
> @@ -286,7 +303,7 @@ static void freeque(struct ipc_namespace
>  }
>  
>  /*
> - * Called with msg_ids.mutex and ipcp locked.
> + * Called with msg_ids.rw_mutex and ipcp locked.
>   */
>  static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
>  {
> @@ -444,7 +461,7 @@ asmlinkage long sys_msgctl(int msqid, in
>  		msginfo.msgmnb = ns->msg_ctlmnb;
>  		msginfo.msgssz = MSGSSZ;
>  		msginfo.msgseg = MSGSEG;
> -		mutex_lock(&msg_ids(ns).mutex);
> +		down_read(&msg_ids(ns).rw_mutex);
>  		if (cmd == MSG_INFO) {
>  			msginfo.msgpool = msg_ids(ns).in_use;
>  			msginfo.msgmap = atomic_read(&msg_hdrs);
> @@ -455,7 +472,7 @@ asmlinkage long sys_msgctl(int msqid, in
>  			msginfo.msgtql = MSGTQL;
>  		}
>  		max_id = ipc_get_maxid(&msg_ids(ns));
> -		mutex_unlock(&msg_ids(ns).mutex);
> +		up_read(&msg_ids(ns).rw_mutex);
>  		if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
>  			return -EFAULT;
>  		return (max_id < 0) ? 0 : max_id;
> @@ -516,8 +533,8 @@ asmlinkage long sys_msgctl(int msqid, in
>  		return  -EINVAL;
>  	}
>  
> -	mutex_lock(&msg_ids(ns).mutex);
> -	msq = msg_lock_check(ns, msqid);
> +	down_write(&msg_ids(ns).rw_mutex);
> +	msq = msg_lock_check_down(ns, msqid);
>  	if (IS_ERR(msq)) {
>  		err = PTR_ERR(msq);
>  		goto out_up;
> @@ -576,7 +593,7 @@ asmlinkage long sys_msgctl(int msqid, in
>  	}
>  	err = 0;
>  out_up:
> -	mutex_unlock(&msg_ids(ns).mutex);
> +	up_write(&msg_ids(ns).rw_mutex);
>  	return err;
>  out_unlock_up:
>  	msg_unlock(msq);
> Index: linux-2.6.23-rc6-mm1/ipc/sem.c
> ===================================================================
> --- linux-2.6.23-rc6-mm1.orig/ipc/sem.c	2007-09-21 10:33:50.000000000 +0200
> +++ linux-2.6.23-rc6-mm1/ipc/sem.c	2007-09-27 10:35:40.000000000 +0200
> @@ -80,7 +80,7 @@
>  #include <linux/audit.h>
>  #include <linux/capability.h>
>  #include <linux/seq_file.h>
> -#include <linux/mutex.h>
> +#include <linux/rwsem.h>
>  #include <linux/nsproxy.h>
>  
>  #include <asm/uaccess.h>
> @@ -148,7 +148,7 @@ void sem_exit_ns(struct ipc_namespace *n
>  	int next_id;
>  	int total, in_use;
>  
> -	mutex_lock(&sem_ids(ns).mutex);
> +	down_write(&sem_ids(ns).rw_mutex);
>  
>  	in_use = sem_ids(ns).in_use;
>  
> @@ -160,7 +160,7 @@ void sem_exit_ns(struct ipc_namespace *n
>  		freeary(ns, sma);
>  		total++;
>  	}
> -	mutex_unlock(&sem_ids(ns).mutex);
> +	up_write(&sem_ids(ns).rw_mutex);
>  
>  	kfree(ns->ids[IPC_SEM_IDS]);
>  	ns->ids[IPC_SEM_IDS] = NULL;
> @@ -174,6 +174,22 @@ void __init sem_init (void)
>  				IPC_SEM_IDS, sysvipc_sem_proc_show);
>  }
>  
> +/*
> + * This routine is called in the paths where the rw_mutex is held to protect
> + * access to the idr tree.
> + */
> +static inline struct sem_array *sem_lock_check_down(struct ipc_namespace *ns,
> +						int id)
> +{
> +	struct kern_ipc_perm *ipcp = ipc_lock_check_down(&sem_ids(ns), id);
> +
> +	return container_of(ipcp, struct sem_array, sem_perm);
> +}
> +
> +/*
> + * sem_lock_(check_) routines are called in the paths where the rw_mutex
> + * is not held.
> + */
>  static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)
>  {
>  	struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id);
> @@ -233,7 +249,7 @@ static inline void sem_rmid(struct ipc_n
>   * @ns: namespace
>   * @params: ptr to the structure that contains key, semflg and nsems
>   *
> - * Called with sem_ids.mutex held
> + * Called with sem_ids.rw_mutex held (as a writer)
>   */
>  
>  static int newary(struct ipc_namespace *ns, struct ipc_params *params)
> @@ -290,7 +306,7 @@ static int newary(struct ipc_namespace *
>  
>  
>  /*
> - * Called with sem_ids.mutex and ipcp locked.
> + * Called with sem_ids.rw_mutex and ipcp locked.
>   */
>  static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
>  {
> @@ -301,7 +317,7 @@ static inline int sem_security(struct ke
>  }
>  
>  /*
> - * Called with sem_ids.mutex and ipcp locked.
> + * Called with sem_ids.rw_mutex and ipcp locked.
>   */
>  static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
>  				struct ipc_params *params)
> @@ -528,9 +544,9 @@ static int count_semzcnt (struct sem_arr
>  	return semzcnt;
>  }
>  
> -/* Free a semaphore set. freeary() is called with sem_ids.mutex locked and
> - * the spinlock for this semaphore set hold. sem_ids.mutex remains locked
> - * on exit.
> +/* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked
> + * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex
> + * remains locked on exit.
>   */
>  static void freeary(struct ipc_namespace *ns, struct sem_array *sma)
>  {
> @@ -615,7 +631,7 @@ static int semctl_nolock(struct ipc_name
>  		seminfo.semmnu = SEMMNU;
>  		seminfo.semmap = SEMMAP;
>  		seminfo.semume = SEMUME;
> -		mutex_lock(&sem_ids(ns).mutex);
> +		down_read(&sem_ids(ns).rw_mutex);
>  		if (cmd == SEM_INFO) {
>  			seminfo.semusz = sem_ids(ns).in_use;
>  			seminfo.semaem = ns->used_sems;
> @@ -624,7 +640,7 @@ static int semctl_nolock(struct ipc_name
>  			seminfo.semaem = SEMAEM;
>  		}
>  		max_id = ipc_get_maxid(&sem_ids(ns));
> -		mutex_unlock(&sem_ids(ns).mutex);
> +		up_read(&sem_ids(ns).rw_mutex);
>  		if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo))) 
>  			return -EFAULT;
>  		return (max_id < 0) ? 0: max_id;
> @@ -895,7 +911,7 @@ static int semctl_down(struct ipc_namesp
>  		if(copy_semid_from_user (&setbuf, arg.buf, version))
>  			return -EFAULT;
>  	}
> -	sma = sem_lock_check(ns, semid);
> +	sma = sem_lock_check_down(ns, semid);
>  	if (IS_ERR(sma))
>  		return PTR_ERR(sma);
>  
> @@ -976,9 +992,9 @@ asmlinkage long sys_semctl (int semid, i
>  		return err;
>  	case IPC_RMID:
>  	case IPC_SET:
> -		mutex_lock(&sem_ids(ns).mutex);
> +		down_write(&sem_ids(ns).rw_mutex);
>  		err = semctl_down(ns,semid,semnum,cmd,version,arg);
> -		mutex_unlock(&sem_ids(ns).mutex);
> +		up_write(&sem_ids(ns).rw_mutex);
>  		return err;
>  	default:
>  		return -EINVAL;
> Index: linux-2.6.23-rc6-mm1/ipc/shm.c
> ===================================================================
> --- linux-2.6.23-rc6-mm1.orig/ipc/shm.c	2007-09-21 10:34:25.000000000 +0200
> +++ linux-2.6.23-rc6-mm1/ipc/shm.c	2007-09-27 10:30:30.000000000 +0200
> @@ -35,7 +35,7 @@
>  #include <linux/capability.h>
>  #include <linux/ptrace.h>
>  #include <linux/seq_file.h>
> -#include <linux/mutex.h>
> +#include <linux/rwsem.h>
>  #include <linux/nsproxy.h>
>  #include <linux/mount.h>
>  
> @@ -83,8 +83,8 @@ static void __shm_init_ns(struct ipc_nam
>  }
>  
>  /*
> - * Called with shm_ids.mutex and the shp structure locked.
> - * Only shm_ids.mutex remains locked on exit.
> + * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
> + * Only shm_ids.rw_mutex remains locked on exit.
>   */
>  static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
>  {
> @@ -115,7 +115,7 @@ void shm_exit_ns(struct ipc_namespace *n
>  	int next_id;
>  	int total, in_use;
>  
> -	mutex_lock(&shm_ids(ns).mutex);
> +	down_write(&shm_ids(ns).rw_mutex);
>  
>  	in_use = shm_ids(ns).in_use;
>  
> @@ -127,7 +127,7 @@ void shm_exit_ns(struct ipc_namespace *n
>  		do_shm_rmid(ns, shp);
>  		total++;
>  	}
> -	mutex_unlock(&shm_ids(ns).mutex);
> +	up_write(&shm_ids(ns).rw_mutex);
>  
>  	kfree(ns->ids[IPC_SHM_IDS]);
>  	ns->ids[IPC_SHM_IDS] = NULL;
> @@ -141,6 +141,31 @@ void __init shm_init (void)
>  				IPC_SHM_IDS, sysvipc_shm_proc_show);
>  }
>  
> +/*
> + * shm_lock_(check_)down routines are called in the paths where the rw_mutex
> + * is held to protect access to the idr tree.
> + */
> +static inline struct shmid_kernel *shm_lock_down(struct ipc_namespace *ns,
> +						int id)
> +{
> +	struct kern_ipc_perm *ipcp = ipc_lock_down(&shm_ids(ns), id);
> +
> +	return container_of(ipcp, struct shmid_kernel, shm_perm);
> +}
> +
> +static inline struct shmid_kernel *shm_lock_check_down(
> +						struct ipc_namespace *ns,
> +						int id)
> +{
> +	struct kern_ipc_perm *ipcp = ipc_lock_check_down(&shm_ids(ns), id);
> +
> +	return container_of(ipcp, struct shmid_kernel, shm_perm);
> +}
> +
> +/*
> + * shm_lock_(check_) routines are called in the paths where the rw_mutex
> + * is not held.
> + */
>  static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
>  {
>  	struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
> @@ -189,7 +214,7 @@ static void shm_open(struct vm_area_stru
>   * @ns: namespace
>   * @shp: struct to free
>   *
> - * It has to be called with shp and shm_ids.mutex locked,
> + * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
>   * but returns with shp unlocked and freed.
>   */
>  static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
> @@ -220,9 +245,9 @@ static void shm_close(struct vm_area_str
>  	struct shmid_kernel *shp;
>  	struct ipc_namespace *ns = sfd->ns;
>  
> -	mutex_lock(&shm_ids(ns).mutex);
> +	down_write(&shm_ids(ns).rw_mutex);
>  	/* remove from the list of attaches of the shm segment */
> -	shp = shm_lock(ns, sfd->id);
> +	shp = shm_lock_down(ns, sfd->id);
>  	BUG_ON(IS_ERR(shp));
>  	shp->shm_lprid = task_tgid_vnr(current);
>  	shp->shm_dtim = get_seconds();
> @@ -232,7 +257,7 @@ static void shm_close(struct vm_area_str
>  		shm_destroy(ns, shp);
>  	else
>  		shm_unlock(shp);
> -	mutex_unlock(&shm_ids(ns).mutex);
> +	up_write(&shm_ids(ns).rw_mutex);
>  }
>  
>  static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> @@ -353,7 +378,7 @@ static struct vm_operations_struct shm_v
>   * @ns: namespace
>   * @params: ptr to the structure that contains key, size and shmflg
>   *
> - * Called with shm_ids.mutex held
> + * Called with shm_ids.rw_mutex held as a writer.
>   */
>  
>  static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
> @@ -442,7 +467,7 @@ no_file:
>  }
>  
>  /*
> - * Called with shm_ids.mutex and ipcp locked.
> + * Called with shm_ids.rw_mutex and ipcp locked.
>   */
>  static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
>  {
> @@ -453,7 +478,7 @@ static inline int shm_security(struct ke
>  }
>  
>  /*
> - * Called with shm_ids.mutex and ipcp locked.
> + * Called with shm_ids.rw_mutex and ipcp locked.
>   */
>  static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
>  				struct ipc_params *params)
> @@ -578,7 +603,7 @@ static inline unsigned long copy_shminfo
>  }
>  
>  /*
> - * Called with shm_ids.mutex held
> + * Called with shm_ids.rw_mutex held as a reader
>   */
>  static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
>  		unsigned long *swp)
> @@ -649,9 +674,9 @@ asmlinkage long sys_shmctl (int shmid, i
>  		if(copy_shminfo_to_user (buf, &shminfo, version))
>  			return -EFAULT;
>  
> -		mutex_lock(&shm_ids(ns).mutex);
> +		down_read(&shm_ids(ns).rw_mutex);
>  		err = ipc_get_maxid(&shm_ids(ns));
> -		mutex_unlock(&shm_ids(ns).mutex);
> +		up_read(&shm_ids(ns).rw_mutex);
>  
>  		if(err<0)
>  			err = 0;
> @@ -666,14 +691,14 @@ asmlinkage long sys_shmctl (int shmid, i
>  			return err;
>  
>  		memset(&shm_info,0,sizeof(shm_info));
> -		mutex_lock(&shm_ids(ns).mutex);
> +		down_read(&shm_ids(ns).rw_mutex);
>  		shm_info.used_ids = shm_ids(ns).in_use;
>  		shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
>  		shm_info.shm_tot = ns->shm_tot;
>  		shm_info.swap_attempts = 0;
>  		shm_info.swap_successes = 0;
>  		err = ipc_get_maxid(&shm_ids(ns));
> -		mutex_unlock(&shm_ids(ns).mutex);
> +		up_read(&shm_ids(ns).rw_mutex);
>  		if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
>  			err = -EFAULT;
>  			goto out;
> @@ -786,8 +811,8 @@ asmlinkage long sys_shmctl (int shmid, i
>  		 *	Instead we set a destroyed flag, and then blow
>  		 *	the name away when the usage hits zero.
>  		 */
> -		mutex_lock(&shm_ids(ns).mutex);
> -		shp = shm_lock_check(ns, shmid);
> +		down_write(&shm_ids(ns).rw_mutex);
> +		shp = shm_lock_check_down(ns, shmid);
>  		if (IS_ERR(shp)) {
>  			err = PTR_ERR(shp);
>  			goto out_up;
> @@ -809,7 +834,7 @@ asmlinkage long sys_shmctl (int shmid, i
>  			goto out_unlock_up;
>  
>  		do_shm_rmid(ns, shp);
> -		mutex_unlock(&shm_ids(ns).mutex);
> +		up_write(&shm_ids(ns).rw_mutex);
>  		goto out;
>  	}
>  
> @@ -824,8 +849,8 @@ asmlinkage long sys_shmctl (int shmid, i
>  			err = -EFAULT;
>  			goto out;
>  		}
> -		mutex_lock(&shm_ids(ns).mutex);
> -		shp = shm_lock_check(ns, shmid);
> +		down_write(&shm_ids(ns).rw_mutex);
> +		shp = shm_lock_check_down(ns, shmid);
>  		if (IS_ERR(shp)) {
>  			err = PTR_ERR(shp);
>  			goto out_up;
> @@ -864,7 +889,7 @@ asmlinkage long sys_shmctl (int shmid, i
>  out_unlock_up:
>  	shm_unlock(shp);
>  out_up:
> -	mutex_unlock(&shm_ids(ns).mutex);
> +	up_write(&shm_ids(ns).rw_mutex);
>  	goto out;
>  out_unlock:
>  	shm_unlock(shp);
> @@ -1000,8 +1025,8 @@ invalid:
>  	fput(file);
>  
>  out_nattch:
> -	mutex_lock(&shm_ids(ns).mutex);
> -	shp = shm_lock(ns, shmid);
> +	down_write(&shm_ids(ns).rw_mutex);
> +	shp = shm_lock_down(ns, shmid);
>  	BUG_ON(IS_ERR(shp));
>  	shp->shm_nattch--;
>  	if(shp->shm_nattch == 0 &&
> @@ -1009,7 +1034,7 @@ out_nattch:
>  		shm_destroy(ns, shp);
>  	else
>  		shm_unlock(shp);
> -	mutex_unlock(&shm_ids(ns).mutex);
> +	up_write(&shm_ids(ns).rw_mutex);
>  
>  out:
>  	return err;
> 
> --
> 

Re: [PATCH -mm1 1/2] fixing idr_find() locking

[Andrew Morton]

On Fri, 28 Sep 2007 08:31:44 +0200 Jarek Poplawski <jarkao2@o2.pl> wrote:

> On Thu, Sep 27, 2007 at 04:33:55PM +0200, Nadia.Derbey@bull.net wrote:
> > [PATCH 01/02]
> > 
> > 
> > This is a patch that fixes the way idr_find() used to be called in ipc_lock():
> > in all the paths that don't imply an update of the ipcs idr, it was called
> > without the idr tree being locked.
> > 
> > The changes are:
> >   . in ipc_ids, the mutex has been changed into a reader/writer semaphore.
> >   . ipc_lock() now takes the mutex as a reader during the idr_find().
> >   . a new routine ipc_lock_down() has been defined: it doesn't take the
> >     mutex, assuming that it is being held by the caller. This is the routine
> >     that is now called in all the update paths.
> > 
> > 
> > Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
> 
> Acked-by: Jarek Poplawski <jarkao2@o2.pl>

thanks.

> PS: there is one big mistake around To/Cc ordering, so I doubt Andrew
> will ever sign this...

Noe, I received and applied it earlier today.

Re: [PATCH -mm1 0/2] Fix unlocked call to idr_find()

[Jarek Poplawski]

On Fri, Sep 28, 2007 at 08:12:56AM +0200, Nadia Derbey wrote:
> Jarek Poplawski wrote:
> >On Thu, Sep 27, 2007 at 04:33:54PM +0200, Nadia.Derbey@bull.net wrote:
> >
> >>This a series of 2 patches that should be applied on top of the other ipc
> >>patches, in 2.6.23-rc6-mm1.
> >
> >...
> >
> >>They should be applied to 2.6.23-rc6-mm1, in the following order:
> >
> >
> >Didn't you mean 2.6.23-rc8-mm1, btw?
> >
> >Regards,
> >Jarek P.
> >
> 
> No, what I wrote is exactly what I meant: unfortunately I couldn't get 
> the rc8-mm1 yet.
> But, Before building the patch, I applied the ipc patches that had been 
> integrated in rc7-mm1.
> Nothing happened in rc8-mm1.
> So you should have no problem appying these patches to your rc8-mm1 tree.

I didn't manage with rc6-mm1, maybe I've messed something.
With rc8-mm2 it's OK - a minor offset only.

Cheers,
Jarek P. 

Re: [PATCH -mm1 1/2] fixing idr_find() locking

[Nadia Derbey]

Jarek Poplawski wrote:
> On Thu, Sep 27, 2007 at 04:33:55PM +0200, Nadia.Derbey@bull.net wrote:
> 
>>[PATCH 01/02]
>>
>>
>>This is a patch that fixes the way idr_find() used to be called in ipc_lock():
>>in all the paths that don't imply an update of the ipcs idr, it was called
>>without the idr tree being locked.
>>
>>The changes are:
>>  . in ipc_ids, the mutex has been changed into a reader/writer semaphore.
>>  . ipc_lock() now takes the mutex as a reader during the idr_find().
>>  . a new routine ipc_lock_down() has been defined: it doesn't take the
>>    mutex, assuming that it is being held by the caller. This is the routine
>>    that is now called in all the update paths.
>>
>>
>>Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
> 
> 
> Acked-by: Jarek Poplawski <jarkao2@o2.pl>
> 
> PS: there is one big mistake around To/Cc ordering, so I doubt Andrew
> will ever sign this...
> 
> 

Jarek,

I thought that since you were the one who pointed out the issue I had to 
put you as the receiver.
Next time I'll also add Andrew in the To list.
Sorry for that.

Regards,
Nadia

Re: [PATCH -mm1 1/2] fixing idr_find() locking

[Jarek Poplawski]

On Fri, Sep 28, 2007 at 09:08:47AM +0200, Nadia Derbey wrote:
> Jarek Poplawski wrote:
> >On Thu, Sep 27, 2007 at 04:33:55PM +0200, Nadia.Derbey@bull.net wrote:
> >
> >>[PATCH 01/02]
> >>
> >>
> >>This is a patch that fixes the way idr_find() used to be called in 
> >>ipc_lock():
> >>in all the paths that don't imply an update of the ipcs idr, it was called
> >>without the idr tree being locked.
> >>
> >>The changes are:
> >> . in ipc_ids, the mutex has been changed into a reader/writer semaphore.
> >> . ipc_lock() now takes the mutex as a reader during the idr_find().
> >> . a new routine ipc_lock_down() has been defined: it doesn't take the
> >>   mutex, assuming that it is being held by the caller. This is the 
> >>   routine
> >>   that is now called in all the update paths.
> >>
> >>
> >>Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
> >
> >
> >Acked-by: Jarek Poplawski <jarkao2@o2.pl>
> >
> >PS: there is one big mistake around To/Cc ordering, so I doubt Andrew
> >will ever sign this...
> >
> >
> 
> Jarek,
> 
> I thought that since you were the one who pointed out the issue I had to 
> put you as the receiver.
> Next time I'll also add Andrew in the To list.
> Sorry for that.

It seems Andrew is generous (sometimes) and should forgive you (some
day...). And I'm perfectly happy. Of course, with Cc too. I'm only
a bit confused with this 2/2, which is of course OK, but it seems my
ack isn't needed there.

Thanks,
Jarek P.