* Ingo Molnar <mingo@xxxxxxx> wrote: > > I recall David Howells had a similar issue with the bootparamter patch > > set. The workaround he used was to add a barrier(); call in the weak > > function to avoid the inline. > > could we add some extra attribute to __weak that would have a similar > effect? Something like __attribute__((noinline)), or something silly > like __attribute__((deprecated)) - just to keep gcc from screwing up > __weak functions? Perhaps adding a section attribute would have a > similar effect? (putting weak definitions into an extra section is > probably helpful anyway) I've applied the patch below to tip/irq/sparseirq - could someone with an affected GCC version please check whether this solves the crash? Ingo -------------------> >From 0d41e654c877a0de441448ca2f63a72ed11c5d84 Mon Sep 17 00:00:00 2001 From: Ingo Molnar <mingo@xxxxxxx> Date: Fri, 26 Dec 2008 14:39:51 +0100 Subject: [PATCH] kbuild, sparseirq: work around GCC bug with __weak aliases Impact: fix panic on null pointer with sparseirq Certain versions of GCC inline the weak global functions. Work it around by marking __weak functions as noinline. Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- include/linux/compiler-gcc.h | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 5c8351b..1ad72e6 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -41,11 +41,17 @@ #define __deprecated __attribute__((deprecated)) #define __packed __attribute__((packed)) -#define __weak __attribute__((weak)) #define __naked __attribute__((naked)) #define __noreturn __attribute__((noreturn)) /* + * Mark weak aliases also noinline, because some GCC versions + * incorrectly inline weak aliases (even when a non-weak variant + * is there) and thus cause crashes: + */ +#define __weak __attribute__((weak)) noinline + +/* * From the GCC manual: * * Many functions have no effects except the return value and their -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
