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>

2 files changed, 3 insertions, 2 deletions

diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c
index 0f69c416eebc..a5432bbbfb88 100644
--- a/fs/jbd/checkpoint.c
+++ b/fs/jbd/checkpoint.c
@@ -347,7 +347,8 @@ restart:
                                 break;
                         }
                         retry = __process_buffer(journal, jh, bhs,&batch_count);
-                        if (!retry && lock_need_resched(&journal->j_list_lock)){
+                        if (!retry && (need_resched() ||
+                                spin_needbreak(&journal->j_list_lock))) {
                                 spin_unlock(&journal->j_list_lock);
                                 retry = 1;
                                 break;
diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c
index 610264b99a8e..31853eb65b4c 100644
--- a/fs/jbd/commit.c
+++ b/fs/jbd/commit.c
@@ -265,7 +265,7 @@ write_out_data:
                         put_bh(bh);
                 }
 
-                if (lock_need_resched(&journal->j_list_lock)) {
+                if (need_resched() || spin_needbreak(&journal->j_list_lock)) {
                         spin_unlock(&journal->j_list_lock);
                         goto write_out_data;
                 }