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| author | Davidlohr Bueso <davidlohr.bueso@hp.com> | 2013-05-01 04:15:19 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-05-01 17:12:57 +0200 |
| commit | 4d2bff5eb86e8d7b4a20934cccb93bdeebed3558 (patch) | |
| tree | 3667eec32ddcf8686335f64db553613c319f0625 /ipc/util.h | |
| parent | ipc: remove bogus lock comment for ipc_checkid (diff) | |
| download | linux-4d2bff5eb86e8d7b4a20934cccb93bdeebed3558.tar.xz linux-4d2bff5eb86e8d7b4a20934cccb93bdeebed3558.zip | |
ipc: introduce obtaining a lockless ipc object
Through ipc_lock() and therefore ipc_lock_check() we currently return the
locked ipc object. This is not necessary for all situations and can,
therefore, cause unnecessary ipc lock contention.
Introduce analogous ipc_obtain_object() and ipc_obtain_object_check()
functions that only lookup and return the ipc object.
Both these functions must be called within the RCU read critical section.
[akpm@linux-foundation.org: propagate the ipc_obtain_object() errno from ipc_lock()]
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Chegu Vinod <chegu_vinod@hp.com>
Acked-by: Michel Lespinasse <walken@google.com>
Cc: Emmanuel Benisty <benisty.e@gmail.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/util.h')
| -rw-r--r-- | ipc/util.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/ipc/util.h b/ipc/util.h index ac1480a4efd1..bfc8d4ea6e46 100644 --- a/ipc/util.h +++ b/ipc/util.h @@ -123,6 +123,7 @@ void ipc_rcu_getref(void *ptr); void ipc_rcu_putref(void *ptr); struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); +struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id); void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); @@ -168,6 +169,7 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm) } struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id); +struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id); int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, struct ipc_ops *ops, struct ipc_params *params); void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, |