diff options
| author | peterz@infradead.org <peterz@infradead.org> | 2023-09-21 12:45:11 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-09-21 19:22:07 +0200 |
| commit | 43adf844951084c266f172561f84c5f8120dd60b (patch) | |
| tree | 6a506adc83de717d2c4bcaa2b3fdded724bba24f /kernel/futex/waitwake.c | |
| parent | 9f6c532f59b20580acf8ede9409c9b8dce6e74e1 (diff) | |
futex: FLAGS_STRICT
The current semantics for futex_wake() are a bit loose, specifically
asking for 0 futexes to be woken actually gets you 1.
Adding a !nr check to sys_futex_wake() makes that it would return 0
for unaligned futex words, because that check comes in the shared
futex_wake() function. Adding the !nr check there, would affect the
legacy sys_futex() semantics.
Hence frob a flag :-(
Suggested-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230921105248.048643656@noisy.programming.kicks-ass.net
Diffstat (limited to 'kernel/futex/waitwake.c')
| -rw-r--r-- | kernel/futex/waitwake.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c index fa9757766103..ceb05b876597 100644 --- a/kernel/futex/waitwake.c +++ b/kernel/futex/waitwake.c @@ -155,6 +155,9 @@ int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) if (unlikely(ret != 0)) return ret; + if ((flags & FLAGS_STRICT) && !nr_wake) + return 0; + hb = futex_hash(&key); /* Make sure we really have tasks to wakeup */ |