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authorNick Piggin <npiggin@suse.de>2008-01-30 07:31:20 -0500
committerIngo Molnar <mingo@elte.hu>2008-01-30 07:31:20 -0500
commit95c354fe9f7d6decc08a92aa26eb233ecc2155bf (patch)
treeec9267032ea875e84216cfb20acb2cfc7c62149f /kernel/sched.c
parenta95d67f87e1a5f1b4429be3ba3bf7b4051657908 (diff)
spinlock: lockbreak cleanup
The break_lock data structure and code for spinlocks is quite nasty. Not only does it double the size of a spinlock but it changes locking to a potentially less optimal trylock. Put all of that under CONFIG_GENERIC_LOCKBREAK, and introduce a __raw_spin_is_contended that uses the lock data itself to determine whether there are waiters on the lock, to be used if CONFIG_GENERIC_LOCKBREAK is not set. Rename need_lockbreak to spin_needbreak, make it use spin_is_contended to decouple it from the spinlock implementation, and make it typesafe (rwlocks do not have any need_lockbreak sites -- why do they even get bloated up with that break_lock then?). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c16
1 files changed, 6 insertions, 10 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 524285e46fa7..ba4c88088f62 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4945,19 +4945,15 @@ EXPORT_SYMBOL(_cond_resched);
4945 */ 4945 */
4946int cond_resched_lock(spinlock_t *lock) 4946int cond_resched_lock(spinlock_t *lock)
4947{ 4947{
4948 int resched = need_resched() && system_state == SYSTEM_RUNNING;
4948 int ret = 0; 4949 int ret = 0;
4949 4950
4950 if (need_lockbreak(lock)) { 4951 if (spin_needbreak(lock) || resched) {
4951 spin_unlock(lock); 4952 spin_unlock(lock);
4952 cpu_relax(); 4953 if (resched && need_resched())
4953 ret = 1; 4954 __cond_resched();
4954 spin_lock(lock); 4955 else
4955 } 4956 cpu_relax();
4956 if (need_resched() && system_state == SYSTEM_RUNNING) {
4957 spin_release(&lock->dep_map, 1, _THIS_IP_);
4958 _raw_spin_unlock(lock);
4959 preempt_enable_no_resched();
4960 __cond_resched();
4961 ret = 1; 4957 ret = 1;
4962 spin_lock(lock); 4958 spin_lock(lock);
4963 } 4959 }