Re: [PATCH 2.6.24-rc3-mm1] IPC: make struct ipc_ids static in ipc_namespace

[Cedric Le Goater <clg@fr.ibm.com>]

Pierre Peiffer wrote:
> 
> Each ipc_namespace contains a table of 3 pointers to struct ipc_ids (3 for
> msg, sem and shm, structure used to store all ipcs)
> These 'struct ipc_ids' are dynamically allocated for each icp_namespace as
> the ipc_namespace itself (for the init namespace, they are initialized with
> pointers to static variables instead)
> 
> It is so for historical reason: in fact, before the use of idr to store the
> ipcs, the ipcs were stored in tables of variable length, depending of the
> maximum number of ipc allowed.
> Now, these 'struct ipc_ids' have a fixed size. As they are allocated in any
> cases for each new ipc_namespace, there is no gain of memory in having them
> allocated separately of the struct ipc_namespace.
> 
> This patch proposes to make this table static in the struct ipc_namespace.
> Thus, we can allocate all in once and get rid of all the code needed to
> allocate and free these ipc_ids separately.

It looks safe and saves quite a lot of line.

Pavel, what do you think of it ? 

Acked-by: Cedric Le Goater <clg@fr.ibm.com>

Thanks,

C.


> Signed-off-by: Pierre Peiffer <pierre.peiffer@bull.net>
> ---
>  include/linux/ipc_namespace.h |   13 +++++++++++--
>  ipc/msg.c                     |   26 ++++----------------------
>  ipc/namespace.c               |   25 ++++---------------------
>  ipc/sem.c                     |   26 ++++----------------------
>  ipc/shm.c                     |   26 ++++----------------------
>  ipc/util.c                    |    6 +++---
>  ipc/util.h                    |   16 ++++------------
>  7 files changed, 34 insertions(+), 104 deletions(-)
> 
> Index: b/include/linux/ipc_namespace.h
> ===================================================================
> --- a/include/linux/ipc_namespace.h
> +++ b/include/linux/ipc_namespace.h
> @@ -2,11 +2,20 @@
>  #define __IPC_NAMESPACE_H__
>  
>  #include <linux/err.h>
> +#include <linux/idr.h>
> +#include <linux/rwsem.h>
> +
> +struct ipc_ids {
> +	int in_use;
> +	unsigned short seq;
> +	unsigned short seq_max;
> +	struct rw_semaphore rw_mutex;
> +	struct idr ipcs_idr;
> +};
>  
> -struct ipc_ids;
>  struct ipc_namespace {
>  	struct kref	kref;
> -	struct ipc_ids	*ids[3];
> +	struct ipc_ids	ids[3];
>  
>  	int		sem_ctls[4];
>  	int		used_sems;
> Index: b/ipc/msg.c
> ===================================================================
> --- a/ipc/msg.c
> +++ b/ipc/msg.c
> @@ -67,9 +67,7 @@ struct msg_sender {
>  #define SEARCH_NOTEQUAL		3
>  #define SEARCH_LESSEQUAL	4
>  
> -static struct ipc_ids init_msg_ids;
> -
> -#define msg_ids(ns)	(*((ns)->ids[IPC_MSG_IDS]))
> +#define msg_ids(ns)	((ns)->ids[IPC_MSG_IDS])
>  
>  #define msg_unlock(msq)		ipc_unlock(&(msq)->q_perm)
>  #define msg_buildid(id, seq)	ipc_buildid(id, seq)
> @@ -80,30 +78,17 @@ static int newque(struct ipc_namespace *
>  static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
>  #endif
>  
> -static void __msg_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
> +void msg_init_ns(struct ipc_namespace *ns)
>  {
> -	ns->ids[IPC_MSG_IDS] = ids;
>  	ns->msg_ctlmax = MSGMAX;
>  	ns->msg_ctlmnb = MSGMNB;
>  	ns->msg_ctlmni = MSGMNI;
>  	atomic_set(&ns->msg_bytes, 0);
>  	atomic_set(&ns->msg_hdrs, 0);
> -	ipc_init_ids(ids);
> +	ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
>  }
>  
>  #ifdef CONFIG_IPC_NS
> -int msg_init_ns(struct ipc_namespace *ns)
> -{
> -	struct ipc_ids *ids;
> -
> -	ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
> -	if (ids == NULL)
> -		return -ENOMEM;
> -
> -	__msg_init_ns(ns, ids);
> -	return 0;
> -}
> -
>  void msg_exit_ns(struct ipc_namespace *ns)
>  {
>  	struct msg_queue *msq;
> @@ -126,15 +111,12 @@ void msg_exit_ns(struct ipc_namespace *n
>  	}
>  
>  	up_write(&msg_ids(ns).rw_mutex);
> -
> -	kfree(ns->ids[IPC_MSG_IDS]);
> -	ns->ids[IPC_MSG_IDS] = NULL;
>  }
>  #endif
>  
>  void __init msg_init(void)
>  {
> -	__msg_init_ns(&init_ipc_ns, &init_msg_ids);
> +	msg_init_ns(&init_ipc_ns);
>  	ipc_init_proc_interface("sysvipc/msg",
>  				"       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
>  				IPC_MSG_IDS, sysvipc_msg_proc_show);
> Index: b/ipc/namespace.c
> ===================================================================
> --- a/ipc/namespace.c
> +++ b/ipc/namespace.c
> @@ -14,35 +14,18 @@
>  
>  static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
>  {
> -	int err;
>  	struct ipc_namespace *ns;
>  
> -	err = -ENOMEM;
>  	ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
>  	if (ns == NULL)
> -		goto err_mem;
> +		return ERR_PTR(-ENOMEM);
>  
> -	err = sem_init_ns(ns);
> -	if (err)
> -		goto err_sem;
> -	err = msg_init_ns(ns);
> -	if (err)
> -		goto err_msg;
> -	err = shm_init_ns(ns);
> -	if (err)
> -		goto err_shm;
> +	sem_init_ns(ns);
> +	msg_init_ns(ns);
> +	shm_init_ns(ns);
>  
>  	kref_init(&ns->kref);
>  	return ns;
> -
> -err_shm:
> -	msg_exit_ns(ns);
> -err_msg:
> -	sem_exit_ns(ns);
> -err_sem:
> -	kfree(ns);
> -err_mem:
> -	return ERR_PTR(err);
>  }
>  
>  struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
> Index: b/ipc/sem.c
> ===================================================================
> --- a/ipc/sem.c
> +++ b/ipc/sem.c
> @@ -87,14 +87,12 @@
>  #include <asm/uaccess.h>
>  #include "util.h"
>  
> -#define sem_ids(ns)	(*((ns)->ids[IPC_SEM_IDS]))
> +#define sem_ids(ns)	((ns)->ids[IPC_SEM_IDS])
>  
>  #define sem_unlock(sma)		ipc_unlock(&(sma)->sem_perm)
>  #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;
> -
>  static int newary(struct ipc_namespace *, struct ipc_params *);
>  static void freeary(struct ipc_namespace *, struct sem_array *);
>  #ifdef CONFIG_PROC_FS
> @@ -118,30 +116,17 @@ static int sysvipc_sem_proc_show(struct 
>  #define sc_semopm	sem_ctls[2]
>  #define sc_semmni	sem_ctls[3]
>  
> -static void __sem_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
> +void sem_init_ns(struct ipc_namespace *ns)
>  {
> -	ns->ids[IPC_SEM_IDS] = ids;
>  	ns->sc_semmsl = SEMMSL;
>  	ns->sc_semmns = SEMMNS;
>  	ns->sc_semopm = SEMOPM;
>  	ns->sc_semmni = SEMMNI;
>  	ns->used_sems = 0;
> -	ipc_init_ids(ids);
> +	ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
>  }
>  
>  #ifdef CONFIG_IPC_NS
> -int sem_init_ns(struct ipc_namespace *ns)
> -{
> -	struct ipc_ids *ids;
> -
> -	ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
> -	if (ids == NULL)
> -		return -ENOMEM;
> -
> -	__sem_init_ns(ns, ids);
> -	return 0;
> -}
> -
>  void sem_exit_ns(struct ipc_namespace *ns)
>  {
>  	struct sem_array *sma;
> @@ -163,15 +148,12 @@ void sem_exit_ns(struct ipc_namespace *n
>  		total++;
>  	}
>  	up_write(&sem_ids(ns).rw_mutex);
> -
> -	kfree(ns->ids[IPC_SEM_IDS]);
> -	ns->ids[IPC_SEM_IDS] = NULL;
>  }
>  #endif
>  
>  void __init sem_init (void)
>  {
> -	__sem_init_ns(&init_ipc_ns, &init_sem_ids);
> +	sem_init_ns(&init_ipc_ns);
>  	ipc_init_proc_interface("sysvipc/sem",
>  				"       key      semid perms      nsems   uid   gid  cuid  cgid      otime      ctime\n",
>  				IPC_SEM_IDS, sysvipc_sem_proc_show);
> Index: b/ipc/util.c
> ===================================================================
> --- a/ipc/util.c
> +++ b/ipc/util.c
> @@ -782,7 +782,7 @@ static void *sysvipc_proc_next(struct se
>  	if (ipc && ipc != SEQ_START_TOKEN)
>  		ipc_unlock(ipc);
>  
> -	return sysvipc_find_ipc(iter->ns->ids[iface->ids], *pos, pos);
> +	return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
>  }
>  
>  /*
> @@ -795,7 +795,7 @@ static void *sysvipc_proc_start(struct s
>  	struct ipc_proc_iface *iface = iter->iface;
>  	struct ipc_ids *ids;
>  
> -	ids = iter->ns->ids[iface->ids];
> +	ids = &iter->ns->ids[iface->ids];
>  
>  	/*
>  	 * Take the lock - this will be released by the corresponding
> @@ -826,7 +826,7 @@ static void sysvipc_proc_stop(struct seq
>  	if (ipc && ipc != SEQ_START_TOKEN)
>  		ipc_unlock(ipc);
>  
> -	ids = iter->ns->ids[iface->ids];
> +	ids = &iter->ns->ids[iface->ids];
>  	/* Release the lock we took in start() */
>  	up_read(&ids->rw_mutex);
>  }
> Index: b/ipc/util.h
> ===================================================================
> --- a/ipc/util.h
> +++ b/ipc/util.h
> @@ -10,7 +10,6 @@
>  #ifndef _IPC_UTIL_H
>  #define _IPC_UTIL_H
>  
> -#include <linux/idr.h>
>  #include <linux/err.h>
>  
>  #define USHRT_MAX 0xffff
> @@ -22,22 +21,14 @@ void shm_init (void);
>  
>  struct ipc_namespace;
>  
> -int sem_init_ns(struct ipc_namespace *ns);
> -int msg_init_ns(struct ipc_namespace *ns);
> -int shm_init_ns(struct ipc_namespace *ns);
> +void sem_init_ns(struct ipc_namespace *ns);
> +void msg_init_ns(struct ipc_namespace *ns);
> +void shm_init_ns(struct ipc_namespace *ns);
>  
>  void sem_exit_ns(struct ipc_namespace *ns);
>  void msg_exit_ns(struct ipc_namespace *ns);
>  void shm_exit_ns(struct ipc_namespace *ns);
>  
> -struct ipc_ids {
> -	int in_use;
> -	unsigned short seq;
> -	unsigned short seq_max;
> -	struct rw_semaphore rw_mutex;
> -	struct idr ipcs_idr;
> -};
> -
>  /*
>   * Structure that holds the parameters needed by the ipc operations
>   * (see after)
> @@ -68,6 +59,7 @@ struct ipc_ops {
>  };
>  
>  struct seq_file;
> +struct ipc_ids;
>  
>  void ipc_init_ids(struct ipc_ids *);
>  #ifdef CONFIG_PROC_FS
> Index: b/ipc/shm.c
> ===================================================================
> --- a/ipc/shm.c
> +++ b/ipc/shm.c
> @@ -56,9 +56,7 @@ struct shm_file_data {
>  static const struct file_operations shm_file_operations;
>  static struct vm_operations_struct shm_vm_ops;
>  
> -static struct ipc_ids init_shm_ids;
> -
> -#define shm_ids(ns)	(*((ns)->ids[IPC_SHM_IDS]))
> +#define shm_ids(ns)	((ns)->ids[IPC_SHM_IDS])
>  
>  #define shm_unlock(shp)			\
>  	ipc_unlock(&(shp)->shm_perm)
> @@ -72,14 +70,13 @@ static void shm_destroy (struct ipc_name
>  static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
>  #endif
>  
> -static void __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
> +void shm_init_ns(struct ipc_namespace *ns)
>  {
> -	ns->ids[IPC_SHM_IDS] = ids;
>  	ns->shm_ctlmax = SHMMAX;
>  	ns->shm_ctlall = SHMALL;
>  	ns->shm_ctlmni = SHMMNI;
>  	ns->shm_tot = 0;
> -	ipc_init_ids(ids);
> +	ipc_init_ids(&ns->ids[IPC_SHM_IDS]);
>  }
>  
>  /*
> @@ -98,18 +95,6 @@ static void do_shm_rmid(struct ipc_names
>  }
>  
>  #ifdef CONFIG_IPC_NS
> -int shm_init_ns(struct ipc_namespace *ns)
> -{
> -	struct ipc_ids *ids;
> -
> -	ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
> -	if (ids == NULL)
> -		return -ENOMEM;
> -
> -	__shm_init_ns(ns, ids);
> -	return 0;
> -}
> -
>  void shm_exit_ns(struct ipc_namespace *ns)
>  {
>  	struct shmid_kernel *shp;
> @@ -131,15 +116,12 @@ void shm_exit_ns(struct ipc_namespace *n
>  		total++;
>  	}
>  	up_write(&shm_ids(ns).rw_mutex);
> -
> -	kfree(ns->ids[IPC_SHM_IDS]);
> -	ns->ids[IPC_SHM_IDS] = NULL;
>  }
>  #endif
>  
>  void __init shm_init (void)
>  {
> -	__shm_init_ns(&init_ipc_ns, &init_shm_ids);
> +	shm_init_ns(&init_ipc_ns);
>  	ipc_init_proc_interface("sysvipc/shm",
>  				"       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
>  				IPC_SHM_IDS, sysvipc_shm_proc_show);
>