Re: 2.6.14-rc3-rt2

[Steven Rostedt]

On Fri, 7 Oct 2005, Ingo Molnar wrote:
>
> * Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> > I was compiling a kernel in a shell that I set to a priority of 20,
> > and it locked up on the bit_spin_lock crap of jbd.  Did you want me to
> > send you that patch again that adds another spinlock to the buffer
> > head and uses that instead of the bit_spins?
>
> yeah, please do.
>

OK, here it is.  I tested it out by doing what locked up the first time.
Compiling the kernel under a shell with a priority of 20.

It survived a "make clean; make -j2".

-- Steve

patched against 2.6.14-rc3-rt10

Index: linux-rt-quilt/fs/buffer.c
===================================================================
--- linux-rt-quilt.orig/fs/buffer.c	2005-10-06 08:04:55.000000000 -0400
+++ linux-rt-quilt/fs/buffer.c	2005-10-07 07:46:25.000000000 -0400
@@ -3055,6 +3055,7 @@
 {
 	BUG_ON(!list_empty(&bh->b_assoc_buffers));
 	BUG_ON(spin_is_locked(&bh->b_uptodate_lock));
+	BUG_ON(spin_is_locked(&bh->b_state_lock));
 	kmem_cache_free(bh_cachep, bh);
 	get_cpu_var(bh_accounting).nr--;
 	recalc_bh_state();
@@ -3072,6 +3073,7 @@
 		memset(bh, 0, sizeof(*bh));
 		INIT_LIST_HEAD(&bh->b_assoc_buffers);
 		spin_lock_init(&bh->b_uptodate_lock);
+		spin_lock_init(&bh->b_state_lock);
 	}
 }

Index: linux-rt-quilt/include/linux/buffer_head.h
===================================================================
--- linux-rt-quilt.orig/include/linux/buffer_head.h	2005-10-06 08:04:56.000000000 -0400
+++ linux-rt-quilt/include/linux/buffer_head.h	2005-10-07 07:46:25.000000000 -0400
@@ -62,6 +62,7 @@
  	void *b_private;		/* reserved for b_end_io */
 	struct list_head b_assoc_buffers; /* associated with another mapping */
 	spinlock_t b_uptodate_lock;
+	spinlock_t b_state_lock;
 };

 /*
Index: linux-rt-quilt/include/linux/jbd.h
===================================================================
--- linux-rt-quilt.orig/include/linux/jbd.h	2005-10-06 08:04:00.000000000 -0400
+++ linux-rt-quilt/include/linux/jbd.h	2005-10-07 07:46:25.000000000 -0400
@@ -327,32 +327,32 @@

 static inline void jbd_lock_bh_state(struct buffer_head *bh)
 {
-	bit_spin_lock(BH_State, &bh->b_state);
+	spin_lock(&bh->b_state_lock);
 }

 static inline int jbd_trylock_bh_state(struct buffer_head *bh)
 {
-	return bit_spin_trylock(BH_State, &bh->b_state);
+	return spin_trylock(&bh->b_state_lock);
 }

 static inline int jbd_is_locked_bh_state(struct buffer_head *bh)
 {
-	return bit_spin_is_locked(BH_State, &bh->b_state);
+	return spin_is_locked(&bh->b_state_lock);
 }

 static inline void jbd_unlock_bh_state(struct buffer_head *bh)
 {
-	bit_spin_unlock(BH_State, &bh->b_state);
+	spin_unlock(&bh->b_state_lock);
 }

 static inline void jbd_lock_bh_journal_head(struct buffer_head *bh)
 {
-	bit_spin_lock(BH_JournalHead, &bh->b_state);
+	spin_lock(&bh->b_uptodate_lock);
 }

 static inline void jbd_unlock_bh_journal_head(struct buffer_head *bh)
 {
-	bit_spin_unlock(BH_JournalHead, &bh->b_state);
+	spin_unlock(&bh->b_uptodate_lock);
 }

 struct jbd_revoke_table_s;

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