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| author | Tejun Heo <tj@kernel.org> | 2016-09-06 18:35:56 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2016-09-06 18:35:56 +0200 |
| commit | 2536524a91fe5c5a9fddd282fd4e79ee0976aefe (patch) | |
| tree | 30eb5b4cd6d9ed4fda69526537d4fac454cbc5e6 /kernel/futex.c | |
| parent | libata: SCT Write Same handle ATA_DFLAG_PIO (diff) | |
| parent | Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert... (diff) | |
| download | linux-2536524a91fe5c5a9fddd282fd4e79ee0976aefe.tar.xz linux-2536524a91fe5c5a9fddd282fd4e79ee0976aefe.zip | |
Merge branch 'master' into for-4.9
Diffstat (limited to 'kernel/futex.c')
| -rw-r--r-- | kernel/futex.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index 33664f70e2d2..46cb3a301bc1 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -179,7 +179,15 @@ int __read_mostly futex_cmpxchg_enabled; * Futex flags used to encode options to functions and preserve them across * restarts. */ -#define FLAGS_SHARED 0x01 +#ifdef CONFIG_MMU +# define FLAGS_SHARED 0x01 +#else +/* + * NOMMU does not have per process address space. Let the compiler optimize + * code away. + */ +# define FLAGS_SHARED 0x00 +#endif #define FLAGS_CLOCKRT 0x02 #define FLAGS_HAS_TIMEOUT 0x04 @@ -405,6 +413,16 @@ static void get_futex_key_refs(union futex_key *key) if (!key->both.ptr) return; + /* + * On MMU less systems futexes are always "private" as there is no per + * process address space. We need the smp wmb nevertheless - yes, + * arch/blackfin has MMU less SMP ... + */ + if (!IS_ENABLED(CONFIG_MMU)) { + smp_mb(); /* explicit smp_mb(); (B) */ + return; + } + switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { case FUT_OFF_INODE: ihold(key->shared.inode); /* implies smp_mb(); (B) */ @@ -436,6 +454,9 @@ static void drop_futex_key_refs(union futex_key *key) return; } + if (!IS_ENABLED(CONFIG_MMU)) + return; + switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) { case FUT_OFF_INODE: iput(key->shared.inode); |