Messages in this thread Patch in this message | | | Date | Tue, 31 Oct 2006 16:09:18 -0800 | From | Andrew Morton <> | Subject | Re: [patch 1/1] schedule removal of FUTEX_FD |
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On Tue, 31 Oct 2006 23:48:11 +0000 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> Ar Maw, 2006-10-31 am 15:09 -0800, ysgrifennodd akpm@osdl.org: > > From: Andrew Morton <akpm@osdl.org> > > > > Apparently FUTEX_FD is unfixably racy and nothing uses it (or if it does, it > > shouldn't). > > > > Add a warning printk, give any remaining users six months to migrate off it. > > Andrew - please use time based rate limits for this sort of thing, that > way you actually get to see who is actually using it. Probably doesn't > matter for the FUTEX_FD case as nobody does, but in general the 'ten > times during boot' approach is not as good as ratelimit(): Perhaps > net_ratelimit() ought to become more general ?
I don't think either works very well, really. How frequently do we rate-limit it? If it's faster than once-per-hour then we'll irritate people.
Maybe that's the answer. Once-per-hour.
umm, I think we'd need something like this:
From: Andrew Morton <akpm@osdl.org>
printk_ratelimit() has global state which makes it not useful for callers which wish to perform ratelimiting at a particular frequency.
Add a printk_timed_ratelimit() which utilises caller-provided state storage to permit more flexibility.
This function can in fact be used for things other than printk ratelimiting and is perhaps poorly named.
Signed-off-by: Andrew Morton <akpm@osdl.org> ---
include/linux/kernel.h | 2 ++ kernel/printk.c | 21 +++++++++++++++++++++ 2 files changed, 23 insertions(+)
diff -puN kernel/printk.c~printk-timed-ratelimit kernel/printk.c --- a/kernel/printk.c~printk-timed-ratelimit +++ a/kernel/printk.c @@ -31,6 +31,7 @@ #include <linux/security.h> #include <linux/bootmem.h> #include <linux/syscalls.h> +#include <linux/jiffies.h> #include <asm/uaccess.h> @@ -1101,3 +1102,23 @@ int printk_ratelimit(void) printk_ratelimit_burst); } EXPORT_SYMBOL(printk_ratelimit); + +/** + * printk_timed_ratelimit - caller-controlled printk ratelimiting + * @caller_jiffies: pointer to caller's state + * @interval_msecs: minimum interval between prints + * + * printk_timed_ratelimit() returns true if more than @interval_msecs + * milliseconds have elapsed since the last time printk_timed_ratelimit() + * returned true. + */ +bool printk_timed_ratelimit(unsigned long *caller_jiffies, + unsigned int interval_msecs) +{ + if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) { + *caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs); + return true; + } + return false; +} +EXPORT_SYMBOL(printk_timed_ratelimit); diff -puN include/linux/kernel.h~printk-timed-ratelimit include/linux/kernel.h --- a/include/linux/kernel.h~printk-timed-ratelimit +++ a/include/linux/kernel.h @@ -171,6 +171,8 @@ __attribute_const__ roundup_pow_of_two(u extern int printk_ratelimit(void); extern int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst); +extern bool printk_timed_ratelimit(unsigned long *caller_jiffies, + unsigned int interval_msec); static inline void console_silent(void) { _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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