On 5/9/07, Sripathi Kodi <[email protected]> wrote:
Hi,
I am trying to fix the BUG I mentioned here:
http://lkml.org/lkml/2007/04/20/41. I noticed that an elegant way to solve
this problem is to have a write_trylock_irqsave helper function. Since we
don't have this now, the code in ptrace_attach implements it using
local_irq_disable and write_trylock. I wish to add write_trylock_irqsave to
mainline kernel and then fix the -rt specific problem using this.
The patch below adds write_trylock_irqsave function.
Why not implement this as follows? That way we're able to (1) be
consistent in style with spin_trylock_irqsave, (2) type fewer lines,
(3) touch fewer files, and (4) not add extra bulk to kernel text size
either.
For the sake of completeness of the API, we could also add a
read_trylock_irqsave, but I'd be against the _irq variants (or should
we call them hazards) that don't save / restore.
Signed-off-by: Satyam Sharma <[email protected]>
---
include/linux/spinlock.h | 7 +++++++
1 file changed, 7 insertions(+)
---
diff -ruNp a/include/linux/spinlock.h b/include/linux/spinlock.h
--- a/include/linux/spinlock.h 2007-04-26 08:38:32.000000000 +0530
+++ b/include/linux/spinlock.h 2007-05-10 08:43:32.000000000 +0530
@@ -282,6 +282,13 @@ do { \
1 : ({ local_irq_restore(flags); 0; }); \
})
+#define write_trylock_irqsave(lock, flags) \
+({ \
+ local_irq_save(flags); \
+ write_trylock(lock) ? \
+ 1 : ({ local_irq_restore(flags); 0; }); \
+})
+
/*
* Locks two spinlocks l1 and l2.
* l1_first indicates if spinlock l1 should be taken first.
-
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