From af91322ef3f29ae4114e736e2a72e28b4d619cf9 Mon Sep 17 00:00:00 2001 From: Dave Young Date: Tue, 22 Sep 2009 16:43:33 -0700 Subject: printk: add printk_delay to make messages readable for some scenarios When syslog is not possible, at the same time there's no serial/net console available, it will be hard to read the printk messages. For example oops/panic/warning messages in shutdown phase. Add a printk delay feature, we can make each printk message delay some milliseconds. Setting the delay by proc/sysctl interface: /proc/sys/kernel/printk_delay The value range from 0 - 10000, default value is 0 [akpm@linux-foundation.org: fix a few things] Signed-off-by: Dave Young Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 2b5b1e0899a8..0a2a19087863 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -246,6 +246,8 @@ extern int printk_ratelimit(void); extern bool printk_timed_ratelimit(unsigned long *caller_jiffies, unsigned int interval_msec); +extern int printk_delay_msec; + /* * Print a one-time message (analogous to WARN_ONCE() et al): */ -- cgit v1.2.3 From 70867453092297be9afb2249e712a1f960ec0a09 Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Tue, 22 Sep 2009 16:43:46 -0700 Subject: printk_once(): use bool for boolean flag Using the type bool (instead of int) for the __print_once flag in the printk_once() macro matches the intent of the code better, and allows the compiler to generate smaller code; eg a typical callsite with gcc 4.3.3 on i386: add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-6 (-6) function old new delta static.__print_once 4 1 -3 get_cpu_vendor 146 143 -3 Saving 6 bytes of object size per callsite by slightly improving the readability of the source seems like a win to me. Signed-off-by: Roland Dreier Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 0a2a19087863..55723afa097b 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -252,10 +252,10 @@ extern int printk_delay_msec; * Print a one-time message (analogous to WARN_ONCE() et al): */ #define printk_once(x...) ({ \ - static int __print_once = 1; \ + static bool __print_once = true; \ \ if (__print_once) { \ - __print_once = 0; \ + __print_once = false; \ printk(x); \ } \ }) -- cgit v1.2.3 From 8c87df457cb58fe75b9b893007917cf8095660a0 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 22 Sep 2009 16:43:52 -0700 Subject: BUILD_BUG_ON(): fix it and a couple of bogus uses of it gcc permitting variable length arrays makes the current construct used for BUILD_BUG_ON() useless, as that doesn't produce any diagnostic if the controlling expression isn't really constant. Instead, this patch makes it so that a bit field gets used here. Consequently, those uses where the condition isn't really constant now also need fixing. Note that in the gfp.h, kmemcheck.h, and virtio_config.h cases MAYBE_BUILD_BUG_ON() really just serves documentation purposes - even if the expression is compile time constant (__builtin_constant_p() yields true), the array is still deemed of variable length by gcc, and hence the whole expression doesn't have the intended effect. [akpm@linux-foundation.org: make arch/sparc/include/asm/vio.h compile] [akpm@linux-foundation.org: more nonsensical assertions in tpm.c..] Signed-off-by: Jan Beulich Cc: Andi Kleen Cc: Rusty Russell Cc: Catalin Marinas Cc: "David S. Miller" Cc: Rajiv Andrade Cc: Mimi Zohar Cc: James Morris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 55723afa097b..63dcaece1ac5 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -678,13 +678,17 @@ struct sysinfo { }; /* Force a compilation error if condition is true */ -#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])) +#define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition)) + +/* Force a compilation error if condition is constant and true */ +#define MAYBE_BUILD_BUG_ON(cond) ((void)sizeof(char[1 - 2 * !!(cond)])) /* Force a compilation error if condition is true, but also produce a result (of value 0 and type size_t), so the expression can be used e.g. in a structure initializer (or where-ever else comma expressions aren't permitted). */ -#define BUILD_BUG_ON_ZERO(e) (sizeof(char[1 - 2 * !!(e)]) - 1) +#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); })) +#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); })) /* Trap pasters of __FUNCTION__ at compile-time */ #define __FUNCTION__ (__func__) -- cgit v1.2.3 From a49c59c042c63b432307c1bbf7dac5a104c786e6 Mon Sep 17 00:00:00 2001 From: Rolf Eike Beer Date: Tue, 22 Sep 2009 16:44:03 -0700 Subject: Make sure the value in abs() does not get truncated if it is greater than 2^32 abs() will truncate the input if is it outside the 2^32 range. Fix that by assuming `long' input. This might generate worse code in the common case. Signed-off-by: Rolf Eike Beer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 63dcaece1ac5..d3cd23f30039 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -146,7 +146,7 @@ extern int _cond_resched(void); #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) #define abs(x) ({ \ - int __x = (x); \ + long __x = (x); \ (__x < 0) ? -__x : __x; \ }) -- cgit v1.2.3