[PATCH 1/2 net-next] libceph: Use sruct_size() in ceph_create_snap_context()

[PATCH 1/2 net-next] libceph: Use sruct_size() in ceph_create_snap_context()

[Christophe JAILLET]

Use sruct_size() instead of hand-writing it.
This makes the code more readable and safer.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
Compile tested only
---
 net/ceph/snapshot.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/net/ceph/snapshot.c b/net/ceph/snapshot.c
index e24315937c45..7363ccebee99 100644
--- a/net/ceph/snapshot.c
+++ b/net/ceph/snapshot.c
@@ -28,11 +28,8 @@ struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
 						gfp_t gfp_flags)
 {
 	struct ceph_snap_context *snapc;
-	size_t size;
 
-	size = sizeof (struct ceph_snap_context);
-	size += snap_count * sizeof (snapc->snaps[0]);
-	snapc = kzalloc(size, gfp_flags);
+	snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);
 	if (!snapc)
 		return NULL;
 
-- 
2.45.1

[PATCH 2/2 net-next] libceph: Use __counted_by() in struct ceph_snap_context

[Christophe JAILLET]

Annotate the 'snaps' flexible array in "struct ceph_snap_context" with
__counted_by() so that additional checks can be made, if enabled.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
Compile tested only
---
 include/linux/ceph/libceph.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
index 4497d0a6772c..485efc8837d5 100644
--- a/include/linux/ceph/libceph.h
+++ b/include/linux/ceph/libceph.h
@@ -164,7 +164,7 @@ struct ceph_snap_context {
 	refcount_t nref;
 	u64 seq;
 	u32 num_snaps;
-	u64 snaps[];
+	u64 snaps[] __counted_by(num_snaps);
 };
 
 extern struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
-- 
2.45.1

Re: [PATCH 1/2 net-next] libceph: Use sruct_size() in ceph_create_snap_context()

[kernel test robot]

Hi Christophe,

kernel test robot noticed the following build errors:

[auto build test ERROR on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Christophe-JAILLET/libceph-Use-__counted_by-in-struct-ceph_snap_context/20240519-172142
base:   net-next/main
patch link:    https://lore.kernel.org/r/5b7c72bdb52703bbfa5511ed500aed4babde1308.1716109606.git.christophe.jaillet%40wanadoo.fr
patch subject: [PATCH 1/2 net-next] libceph: Use sruct_size() in ceph_create_snap_context()
config: i386-allmodconfig (https://download.01.org/0day-ci/archive/20240519/202405191909.7qhhefnu-lkp@intel.com/config)
compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240519/202405191909.7qhhefnu-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405191909.7qhhefnu-lkp@intel.com/

All errors (new ones prefixed by >>):

   net/ceph/snapshot.c: In function 'ceph_create_snap_context':
>> net/ceph/snapshot.c:32:25: error: implicit declaration of function 'sruct_size'; did you mean 'struct_size'? [-Werror=implicit-function-declaration]
      32 |         snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);
         |                         ^~~~~~~~~~
         |                         struct_size
>> net/ceph/snapshot.c:32:43: error: 'snaps' undeclared (first use in this function); did you mean 'snapc'?
      32 |         snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);
         |                                           ^~~~~
         |                                           snapc
   net/ceph/snapshot.c:32:43: note: each undeclared identifier is reported only once for each function it appears in
   cc1: some warnings being treated as errors


vim +32 net/ceph/snapshot.c

    11	
    12	/*
    13	 * Ceph snapshot contexts are reference counted objects, and the
    14	 * returned structure holds a single reference.  Acquire additional
    15	 * references with ceph_get_snap_context(), and release them with
    16	 * ceph_put_snap_context().  When the reference count reaches zero
    17	 * the entire structure is freed.
    18	 */
    19	
    20	/*
    21	 * Create a new ceph snapshot context large enough to hold the
    22	 * indicated number of snapshot ids (which can be 0).  Caller has
    23	 * to fill in snapc->seq and snapc->snaps[0..snap_count-1].
    24	 *
    25	 * Returns a null pointer if an error occurs.
    26	 */
    27	struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
    28							gfp_t gfp_flags)
    29	{
    30		struct ceph_snap_context *snapc;
    31	
  > 32		snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);
    33		if (!snapc)
    34			return NULL;
    35	
    36		refcount_set(&snapc->nref, 1);
    37		snapc->num_snaps = snap_count;
    38	
    39		return snapc;
    40	}
    41	EXPORT_SYMBOL(ceph_create_snap_context);
    42	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 1/2 net-next] libceph: Use sruct_size() in ceph_create_snap_context()

[Christophe JAILLET]

Le 19/05/2024 à 13:34, kernel test robot a écrit :
> Hi Christophe,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on net-next/main]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Christophe-JAILLET/libceph-Use-__counted_by-in-struct-ceph_snap_context/20240519-172142
> base:   net-next/main
> patch link:    https://lore.kernel.org/r/5b7c72bdb52703bbfa5511ed500aed4babde1308.1716109606.git.christophe.jaillet%40wanadoo.fr
> patch subject: [PATCH 1/2 net-next] libceph: Use sruct_size() in ceph_create_snap_context()
> config: i386-allmodconfig (https://download.01.org/0day-ci/archive/20240519/202405191909.7qhhefnu-lkp@intel.com/config)
> compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240519/202405191909.7qhhefnu-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202405191909.7qhhefnu-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>     net/ceph/snapshot.c: In function 'ceph_create_snap_context':
>>> net/ceph/snapshot.c:32:25: error: implicit declaration of function 'sruct_size'; did you mean 'struct_size'? [-Werror=implicit-function-declaration]
>        32 |         snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);
>           |                         ^~~~~~~~~~
>           |                         struct_size
>>> net/ceph/snapshot.c:32:43: error: 'snaps' undeclared (first use in this function); did you mean 'snapc'?
>        32 |         snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);
>           |                                           ^~~~~
>           |                                           snapc
>     net/ceph/snapshot.c:32:43: note: each undeclared identifier is reported only once for each function it appears in
>     cc1: some warnings being treated as errors
> 
> 
> vim +32 net/ceph/snapshot.c
> 
>      11	
>      12	/*
>      13	 * Ceph snapshot contexts are reference counted objects, and the
>      14	 * returned structure holds a single reference.  Acquire additional
>      15	 * references with ceph_get_snap_context(), and release them with
>      16	 * ceph_put_snap_context().  When the reference count reaches zero
>      17	 * the entire structure is freed.
>      18	 */
>      19	
>      20	/*
>      21	 * Create a new ceph snapshot context large enough to hold the
>      22	 * indicated number of snapshot ids (which can be 0).  Caller has
>      23	 * to fill in snapc->seq and snapc->snaps[0..snap_count-1].
>      24	 *
>      25	 * Returns a null pointer if an error occurs.
>      26	 */
>      27	struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
>      28							gfp_t gfp_flags)
>      29	{
>      30		struct ceph_snap_context *snapc;
>      31	
>    > 32		snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);

Ouch!

this was build-tested, but I must have made a mistake when editing the 
patch file to add the "net-next".

Sorry about that.
I'll resend when the net-next branch will re-open.

CJ

>      33		if (!snapc)
>      34			return NULL;
>      35	
>      36		refcount_set(&snapc->nref, 1);
>      37		snapc->num_snaps = snap_count;
>      38	
>      39		return snapc;
>      40	}
>      41	EXPORT_SYMBOL(ceph_create_snap_context);
>      42	
> 

Re: [PATCH 1/2 net-next] libceph: Use sruct_size() in ceph_create_snap_context()

[kernel test robot]

Hi Christophe,

kernel test robot noticed the following build errors:

[auto build test ERROR on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Christophe-JAILLET/libceph-Use-__counted_by-in-struct-ceph_snap_context/20240519-172142
base:   net-next/main
patch link:    https://lore.kernel.org/r/5b7c72bdb52703bbfa5511ed500aed4babde1308.1716109606.git.christophe.jaillet%40wanadoo.fr
patch subject: [PATCH 1/2 net-next] libceph: Use sruct_size() in ceph_create_snap_context()
config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20240519/202405191916.QmDasdJ5-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240519/202405191916.QmDasdJ5-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405191916.QmDasdJ5-lkp@intel.com/

All errors (new ones prefixed by >>):

>> net/ceph/snapshot.c:32:18: error: call to undeclared function 'sruct_size'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
      32 |         snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);
         |                         ^
>> net/ceph/snapshot.c:32:36: error: use of undeclared identifier 'snaps'; did you mean 'snapc'?
      32 |         snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);
         |                                           ^~~~~
         |                                           snapc
   net/ceph/snapshot.c:30:28: note: 'snapc' declared here
      30 |         struct ceph_snap_context *snapc;
         |                                   ^
   2 errors generated.


vim +/sruct_size +32 net/ceph/snapshot.c

    11	
    12	/*
    13	 * Ceph snapshot contexts are reference counted objects, and the
    14	 * returned structure holds a single reference.  Acquire additional
    15	 * references with ceph_get_snap_context(), and release them with
    16	 * ceph_put_snap_context().  When the reference count reaches zero
    17	 * the entire structure is freed.
    18	 */
    19	
    20	/*
    21	 * Create a new ceph snapshot context large enough to hold the
    22	 * indicated number of snapshot ids (which can be 0).  Caller has
    23	 * to fill in snapc->seq and snapc->snaps[0..snap_count-1].
    24	 *
    25	 * Returns a null pointer if an error occurs.
    26	 */
    27	struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
    28							gfp_t gfp_flags)
    29	{
    30		struct ceph_snap_context *snapc;
    31	
  > 32		snapc = kzalloc(sruct_size(snapc, snaps, snap_count), gfp_flags);
    33		if (!snapc)
    34			return NULL;
    35	
    36		refcount_set(&snapc->nref, 1);
    37		snapc->num_snaps = snap_count;
    38	
    39		return snapc;
    40	}
    41	EXPORT_SYMBOL(ceph_create_snap_context);
    42	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki