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* [PATCH] ceph: Convert from atomic_t to refcount_t on ceph_snap_realm->nref
@ 2021-07-17 10:06 Xiyu Yang
  2021-07-17 11:21 ` Jeff Layton
                   ` (2 more replies)
  0 siblings, 3 replies; 9+ messages in thread
From: Xiyu Yang @ 2021-07-17 10:06 UTC (permalink / raw)
  To: Jeff Layton, Ilya Dryomov, ceph-devel, linux-kernel
  Cc: yuanxzhang, Xiyu Yang, Xin Tan

refcount_t type and corresponding API can protect refcounters from
accidental underflow and overflow and further use-after-free situations.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
---
 fs/ceph/snap.c  | 15 ++++++++-------
 fs/ceph/super.h |  3 ++-
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 4ac0606dcbd4..d4ec9c5118bd 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -68,14 +68,15 @@ void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
 	lockdep_assert_held(&mdsc->snap_rwsem);
 
 	dout("get_realm %p %d -> %d\n", realm,
-	     atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
+	     refcount_read(&realm->nref), refcount_read(&realm->nref)+1);
 	/*
 	 * since we _only_ increment realm refs or empty the empty
 	 * list with snap_rwsem held, adjusting the empty list here is
 	 * safe.  we do need to protect against concurrent empty list
 	 * additions, however.
 	 */
-	if (atomic_inc_return(&realm->nref) == 1) {
+	refcount_inc(&realm->nref);
+	if (refcount_read(&realm->nref) == 1) {
 		spin_lock(&mdsc->snap_empty_lock);
 		list_del_init(&realm->empty_item);
 		spin_unlock(&mdsc->snap_empty_lock);
@@ -121,7 +122,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
 	if (!realm)
 		return ERR_PTR(-ENOMEM);
 
-	atomic_set(&realm->nref, 1);    /* for caller */
+	refcount_set(&realm->nref, 1);    /* for caller */
 	realm->ino = ino;
 	INIT_LIST_HEAD(&realm->children);
 	INIT_LIST_HEAD(&realm->child_item);
@@ -209,8 +210,8 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
 	lockdep_assert_held_write(&mdsc->snap_rwsem);
 
 	dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
-	     atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
-	if (atomic_dec_and_test(&realm->nref))
+	     refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
+	if (refcount_dec_and_test(&realm->nref))
 		__destroy_snap_realm(mdsc, realm);
 }
 
@@ -221,8 +222,8 @@ void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
 			 struct ceph_snap_realm *realm)
 {
 	dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
-	     atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
-	if (!atomic_dec_and_test(&realm->nref))
+	     refcount_read(&realm->nref), refcount_read(&realm->nref)-1);
+	if (!refcount_dec_and_test(&realm->nref))
 		return;
 
 	if (down_write_trylock(&mdsc->snap_rwsem)) {
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 6b6332a5c113..3abb00d7a0eb 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -2,6 +2,7 @@
 #ifndef _FS_CEPH_SUPER_H
 #define _FS_CEPH_SUPER_H
 
+#include <linux/refcount.h>
 #include <linux/ceph/ceph_debug.h>
 
 #include <asm/unaligned.h>
@@ -859,7 +860,7 @@ struct ceph_readdir_cache_control {
 struct ceph_snap_realm {
 	u64 ino;
 	struct inode *inode;
-	atomic_t nref;
+	refcount_t nref;
 	struct rb_node node;
 
 	u64 created, seq;
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 9+ messages in thread
* Re: [PATCH] ceph: Convert from atomic_t to refcount_t on ceph_snap_realm->nref
@ 2021-07-19  3:18 kernel test robot
  0 siblings, 0 replies; 9+ messages in thread
From: kernel test robot @ 2021-07-19  3:18 UTC (permalink / raw)
  To: kbuild

[-- Attachment #1: Type: text/plain, Size: 3997 bytes --]

CC: kbuild-all(a)lists.01.org
In-Reply-To: <1626516381-40440-1-git-send-email-xiyuyang19@fudan.edu.cn>
References: <1626516381-40440-1-git-send-email-xiyuyang19@fudan.edu.cn>
TO: Xiyu Yang <xiyuyang19@fudan.edu.cn>
TO: Jeff Layton <jlayton@kernel.org>
TO: Ilya Dryomov <idryomov@gmail.com>
TO: ceph-devel(a)vger.kernel.org
TO: linux-kernel(a)vger.kernel.org
CC: yuanxzhang(a)fudan.edu.cn
CC: Xiyu Yang <xiyuyang19@fudan.edu.cn>
CC: Xin Tan <tanxin.ctf@gmail.com>

Hi Xiyu,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on ceph-client/for-linus]
[also build test WARNING on v5.14-rc2 next-20210716]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Xiyu-Yang/ceph-Convert-from-atomic_t-to-refcount_t-on-ceph_snap_realm-nref/20210718-111108
base:   https://github.com/ceph/ceph-client.git for-linus
:::::: branch date: 24 hours ago
:::::: commit date: 24 hours ago
config: x86_64-rhel-8.3-kselftests (attached as .config)
compiler: gcc-10 (Ubuntu 10.3.0-1ubuntu1~20.04) 10.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-341-g8af24329-dirty
        # https://github.com/0day-ci/linux/commit/af8e5c68ccb6a1e5aead78e10d6d0441c032ba66
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Xiyu-Yang/ceph-Convert-from-atomic_t-to-refcount_t-on-ceph_snap_realm-nref/20210718-111108
        git checkout af8e5c68ccb6a1e5aead78e10d6d0441c032ba66
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=x86_64 SHELL=/bin/bash fs/ceph/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)
   fs/ceph/quota.c: note: in included file (through fs/ceph/super.h):
   include/linux/ceph/ceph_debug.h:5:9: sparse: sparse: preprocessor token pr_fmt redefined
   fs/ceph/quota.c: note: in included file (through include/linux/kernel.h, include/asm-generic/bug.h, arch/x86/include/asm/bug.h, ...):
>> include/linux/printk.h:301:9: sparse: this was the original definition

vim +301 include/linux/printk.h

01c313dded34a1 Arnd Bergmann   2017-11-13  286  
90c165f0de3ada Ricardo Cañuelo 2020-04-03  287  /**
90c165f0de3ada Ricardo Cañuelo 2020-04-03  288   * pr_fmt - used by the pr_*() macros to generate the printk format string
90c165f0de3ada Ricardo Cañuelo 2020-04-03  289   * @fmt: format string passed from a pr_*() macro
90c165f0de3ada Ricardo Cañuelo 2020-04-03  290   *
90c165f0de3ada Ricardo Cañuelo 2020-04-03  291   * This macro can be used to generate a unified format string for pr_*()
90c165f0de3ada Ricardo Cañuelo 2020-04-03  292   * macros. A common use is to prefix all pr_*() messages in a file with a common
90c165f0de3ada Ricardo Cañuelo 2020-04-03  293   * string. For example, defining this at the top of a source file:
90c165f0de3ada Ricardo Cañuelo 2020-04-03  294   *
90c165f0de3ada Ricardo Cañuelo 2020-04-03  295   *        #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
90c165f0de3ada Ricardo Cañuelo 2020-04-03  296   *
90c165f0de3ada Ricardo Cañuelo 2020-04-03  297   * would prefix all pr_info, pr_emerg... messages in the file with the module
90c165f0de3ada Ricardo Cañuelo 2020-04-03  298   * name.
90c165f0de3ada Ricardo Cañuelo 2020-04-03  299   */
968ab1838a5d48 Linus Torvalds  2010-11-15  300  #ifndef pr_fmt
968ab1838a5d48 Linus Torvalds  2010-11-15 @301  #define pr_fmt(fmt) fmt
968ab1838a5d48 Linus Torvalds  2010-11-15  302  #endif
968ab1838a5d48 Linus Torvalds  2010-11-15  303  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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2021-07-17 10:06 [PATCH] ceph: Convert from atomic_t to refcount_t on ceph_snap_realm->nref Xiyu Yang
2021-07-17 11:21 ` Jeff Layton
2021-07-17 12:26   ` Xiyu Yang
2021-07-17 13:40     ` Jeff Layton
2021-07-18 19:58 ` kernel test robot
2021-07-18 19:58   ` kernel test robot
2021-07-18 20:02 ` kernel test robot
2021-07-18 20:02   ` kernel test robot
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