Re: Kernel crash after using new Intel NIC (igb)
From: Arun Sharma <hidden>
Date: 2011-05-27 21:14:27
Also in:
lkml
Subsystem:
atomic infrastructure, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Will Deacon, Peter Zijlstra, Boqun Feng, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
On Fri, May 27, 2011 at 09:56:59PM +0200, Eric Dumazet wrote:
quoted
This looks very similar to atomic_add_unless(). If we had a __atomic_add_unless() that returned "old", we could then do: atomic_add_unless() { return __atomic_add_unless() != u } atomic_add_unless_return() { return __atomic_add_unless() + a}Sure ! I preferred to not touch lot of files in kernel (atomic_add_unless() is defined in several files) because its a stable candidate patch (2.6.36+) So a cleanup patch for 2.6.40+ is certainly doable, do you want to do this ?
The attached works for me for x86_64. Cc'ing Ingo/Thomas for comment. -Arun atomic: Refactor atomic_add_unless Commit 686a7e3 (inetpeer: fix race in unused_list manipulations) in net-2.6 added a atomic_add_unless_return() variant that tries to detect 0->1 transitions of an atomic reference count. This sounds like a generic functionality that could be expressed in terms of an __atomic_add_unless() that returned the old value instead of a bool. Signed-off-by: Arun Sharma <redacted> --- arch/x86/include/asm/atomic.h | 22 ++++++++++++++++++---- 1 files changed, 18 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
index 952a826..bbdbffe 100644
--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h@@ -221,15 +221,15 @@ static inline int atomic_xchg(atomic_t *v, int new) } /** - * atomic_add_unless - add unless the number is already a given value + * __atomic_add_unless - add unless the number is already a given value * @v: pointer of type atomic_t * @a: the amount to add to v... * @u: ...unless v is equal to u. * * Atomically adds @a to @v, so long as @v was not already @u. - * Returns non-zero if @v was not @u, and zero otherwise. + * Returns the old value of v */ -static inline int atomic_add_unless(atomic_t *v, int a, int u) +static inline int __atomic_add_unless(atomic_t *v, int a, int u) { int c, old; c = atomic_read(v);
@@ -241,7 +241,21 @@ static inline int atomic_add_unless(atomic_t *v, int a, int u) break; c = old; } - return c != (u); + return c; +} + +/** + * atomic_add_unless - add unless the number is already a given value + * @v: pointer of type atomic_t + * @a: the amount to add to v... + * @u: ...unless v is equal to u. + * + * Atomically adds @a to @v, so long as @v was not already @u. + * Returns non-zero if @v was not @u, and zero otherwise. + */ +static inline int atomic_add_unless(atomic_t *v, int a, int u) +{ + return __atomic_add_unless(v, a, u) != u; } #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
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1.7.4