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futex: Split out the first waiter attachment from lookup_pi_state() 

upstream commit: 04e1b2e52b

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 <tglx@linutronix.de>
Reviewed-by: Darren Hart <darren@dvhart.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Kees Cook <kees@outflux.net>
Cc: wad@chromium.org
Link: http://lkml.kernel.org/r/20140611204237.271300614@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Thomas Gleixner 2014-06-11 20:45:40 +00:00 committed by Alibek Omarov
parent 16268bd779
commit c3cefde051
1 changed files with 28 additions and 14 deletions
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42
kernel/futex.c
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@ -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