From ff52e4300e141846502f2648389c341246c8ce63 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 11 Jun 2014 20:45:40 +0000 Subject: futex: Split out the first waiter attachment from lookup_pi_state() upstream commit: 04e1b2e52b17195c9a1daa5935c55a4c8716095c We want to be a bit more clever in futex_lock_pi_atomic() and separate the possible states. Split out the code which attaches the first waiter to the owner into a separate function. No functional change. Signed-off-by: Thomas Gleixner Reviewed-by: Darren Hart Cc: Peter Zijlstra Cc: Davidlohr Bueso Cc: Kees Cook Cc: wad@chromium.org Link: http://lkml.kernel.org/r/20140611204237.271300614@linutronix.de Signed-off-by: Thomas Gleixner Signed-off-by: Steven Rostedt --- kernel/futex.c | 42 ++++++++++++++++++++++++++++-------------- 1 file changed, 28 insertions(+), 14 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index 8377eec3f650..e0802beff9ad 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -855,21 +855,16 @@ out_state: return 0; } -static int -lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, - union futex_key *key, struct futex_pi_state **ps) +/* + * Lookup the task for the TID provided from user space and attach to + * it after doing proper sanity checks. + */ +static int attach_to_pi_owner(u32 uval, union futex_key *key, + struct futex_pi_state **ps) { - struct futex_q *match = futex_top_waiter(hb, key); - struct futex_pi_state *pi_state = NULL; - struct task_struct *p; pid_t pid = uval & FUTEX_TID_MASK; - - /* - * If there is a waiter on that futex, validate it and - * attach to the pi_state when the validation succeeds. - */ - if (match) - return attach_to_pi_state(uval, match->pi_state, ps); + struct futex_pi_state *pi_state; + struct task_struct *p; /* * We are the first waiter - try to look up the real owner and attach @@ -912,7 +907,7 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, pi_state = alloc_pi_state(); /* - * Initialize the pi_mutex in locked state and make 'p' + * Initialize the pi_mutex in locked state and make @p * the owner of it: */ rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p); @@ -932,6 +927,25 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, return 0; } +static int lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, + union futex_key *key, struct futex_pi_state **ps) +{ + struct futex_q *match = futex_top_waiter(hb, key); + + /* + * If there is a waiter on that futex, validate it and + * attach to the pi_state when the validation succeeds. + */ + if (match) + return attach_to_pi_state(uval, match->pi_state, ps); + + /* + * We are the first waiter - try to look up the owner based on + * @uval and attach to it. + */ + return attach_to_pi_owner(uval, key, ps); +} + /** * futex_lock_pi_atomic() - Atomic work required to acquire a pi aware futex * @uaddr: the pi futex user address -- cgit v1.2.3