diff options
author | 2017-07-12 14:34:38 -0700 | |
---|---|---|
committer | 2017-07-12 16:26:01 -0700 | |
commit | 1a23395672658969a4035dcc518ea6cab835c579 (patch) | |
tree | 1d12f7f1f215a186c9ebe31f1fb91db00f9dae1a /include/linux/sem.h | |
parent | fault-inject: support systematic fault injection (diff) | |
download | linux-1a23395672658969a4035dcc518ea6cab835c579.tar.gz linux-1a23395672658969a4035dcc518ea6cab835c579.tar.bz2 linux-1a23395672658969a4035dcc518ea6cab835c579.zip |
ipc/sem.c: remove sem_base, embed struct sem
sma->sem_base is initialized with
sma->sem_base = (struct sem *) &sma[1];
The current code has four problems:
- There is an unnecessary pointer dereference - sem_base is not needed.
- Alignment for struct sem only works by chance.
- The current code causes false positive for static code analysis.
- This is a cast between different non-void types, which the future
randstruct GCC plugin warns on.
And, as bonus, the code size gets smaller:
Before:
0 .text 00003770
After:
0 .text 0000374e
[manfred@colorfullife.com: s/[0]/[]/, per hch]
Link: http://lkml.kernel.org/r/20170525185107.12869-2-manfred@colorfullife.com
Link: http://lkml.kernel.org/r/20170515171912.6298-2-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: <1vier1@web.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/sem.h')
-rw-r--r-- | include/linux/sem.h | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/include/linux/sem.h b/include/linux/sem.h index 9edec926e9d9..9db14093b73c 100644 --- a/include/linux/sem.h +++ b/include/linux/sem.h @@ -8,11 +8,29 @@ struct task_struct; +/* One semaphore structure for each semaphore in the system. */ +struct sem { + int semval; /* current value */ + /* + * PID of the process that last modified the semaphore. For + * Linux, specifically these are: + * - semop + * - semctl, via SETVAL and SETALL. + * - at task exit when performing undo adjustments (see exit_sem). + */ + int sempid; + spinlock_t lock; /* spinlock for fine-grained semtimedop */ + struct list_head pending_alter; /* pending single-sop operations */ + /* that alter the semaphore */ + struct list_head pending_const; /* pending single-sop operations */ + /* that do not alter the semaphore*/ + time_t sem_otime; /* candidate for sem_otime */ +} ____cacheline_aligned_in_smp; + /* One sem_array data structure for each set of semaphores in the system. */ struct sem_array { struct kern_ipc_perm sem_perm; /* permissions .. see ipc.h */ time_t sem_ctime; /* last change time */ - struct sem *sem_base; /* ptr to first semaphore in array */ struct list_head pending_alter; /* pending operations */ /* that alter the array */ struct list_head pending_const; /* pending complex operations */ @@ -21,6 +39,8 @@ struct sem_array { int sem_nsems; /* no. of semaphores in array */ int complex_count; /* pending complex operations */ unsigned int use_global_lock;/* >0: global lock required */ + + struct sem sems[]; }; #ifdef CONFIG_SYSVIPC |