Arjan van de Ven пишет:
> Subject: move WARN_ON() out of line
> From: Arjan van de Ven <[EMAIL PROTECTED]>
> CC: Ingo Molnar <[EMAIL PROTECTED]>
> CC: Andrew Morton <[EMAIL PROTECTED]>
>
> A quick grep shows that there are currently 1145 instances of WARN_ON
> in the kernel. Currently, WARN_ON is pretty much entirely inlined,
> which makes it hard to enhance it without growing the size of the kernel
> (and getting Andrew unhappy).
>
> This patch moves WARN_ON() out of line entirely. I've considered keeping
> the test inline and moving only the slowpath out of line, but I decided
> against that: an out of line test reduces the pressure on the CPUs
> branch predictor logic and gives smaller code, while a function call
> to a fixed location is quite fast. Likewise I've considered doing something
> similar to BUG() (eg use a trapping instruction) but that's not really
> better (it needs the test inline again and recovering from an invalid
> instruction isn't quite fun).
>
> The code size reduction of this patch was about 6.5Kb (on a distro style
> .config):
>
> text data bss dec hex filename
> 3096493 293455 2760704 6150652 5dd9fc vmlinux.before
> 3090006 293455 2760704 6144165 5dc0a5 vmlinux.after
>
> Signed-off-by: Arjan van de Ven <[EMAIL PROTECTED]>
>
> ---
> include/asm-generic/bug.h | 13 ++++---------
> kernel/panic.c | 13 +++++++++++++
> 2 files changed, 17 insertions(+), 9 deletions(-)
>
> Index: linux-2.6.24-rc6/include/asm-generic/bug.h
> ===================================================================
> --- linux-2.6.24-rc6.orig/include/asm-generic/bug.h
> +++ linux-2.6.24-rc6/include/asm-generic/bug.h
> @@ -32,15 +32,10 @@ struct bug_entry {
> #endif
>
> #ifndef HAVE_ARCH_WARN_ON
> -#define WARN_ON(condition) ({ \
> - int __ret_warn_on = !!(condition); \
> - if (unlikely(__ret_warn_on)) { \
> - printk("WARNING: at %s:%d %s()\n", __FILE__, \
> - __LINE__, __FUNCTION__); \
> - dump_stack(); \
> - } \
> - unlikely(__ret_warn_on); \
> -})
> +extern int do_warn_on(const unsigned long condition, const char *file,
> + const int line, const char *function);
> +#define WARN_ON(condition) do_warn_on((unsigned long)(condition),
> __FILE__, \
> + __LINE__, __FUNCTION__)
> #endif
>
> #else /* !CONFIG_BUG */
> Index: linux-2.6.24-rc6/kernel/panic.c
> ===================================================================
> --- linux-2.6.24-rc6.orig/kernel/panic.c
> +++ linux-2.6.24-rc6/kernel/panic.c
> @@ -20,6 +20,7 @@
> #include <linux/kexec.h>
> #include <linux/debug_locks.h>
> #include <linux/random.h>
> +#include <asm/bug.h>
>
> int panic_on_oops;
> int tainted;
> @@ -292,6 +293,18 @@ void oops_exit(void)
> (unsigned long long)oops_id);
> }
>
> +int do_warn_on(const unsigned long condition, const char *file,
> + const int line, const char *function)
> +{
> + if (unlikely(condition)) {
> + printk(KERN_WARNING "WARNING: at %s:%d %s()\n",
> + __FILE__, __LINE__, __FUNCTION__);
Isn't this going to print "panic.c" for __FILE__, "do_warn_on" for __FUNCTION__
and whatever line number you have there for __LINE__? I put up a userspace
equivalent
of what you're doing here, which confirms my suspision:
[EMAIL PROTECTED]:/tmp$ cat c.c
#include <stdio.h>
#define WARN_ON(condition) do_warn_on((unsigned long)(condition), __FILE__, \
__LINE__, __FUNCTION__)
int do_warn_on(const unsigned long condition, const char *file,
const int line, const char *function)
{
if (condition) {
printf("WARNING: at %s:%d %s()\n",
__FILE__, __LINE__, __FUNCTION__);
}
return !!condition;
}
int main()
{
WARN_ON(1);
return 0;
}
[EMAIL PROTECTED]:/tmp$ cc c.c
[EMAIL PROTECTED]:/tmp$ ./a.out
WARNING: at c.c:11 do_warn_on()
[EMAIL PROTECTED]:/tmp$
I think that your intention was to propagate the parameters to the do_warn_on()
routine
to the printk() call, right?
> + dump_stack();
> + }
> + return !!condition;
> +}
> +EXPORT_SYMBOL(do_warn_on);
> +
> #ifdef CONFIG_CC_STACKPROTECTOR
> /*
> * Called when gcc's -fstack-protector feature is used, and
> --
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