Subject: + coredump-cn_vprintf-has-no-reason-to-call-vsnprintf-twice.patch added to -mm tree
To: oleg@xxxxxxxxxx,andi@xxxxxxxxxxxxxx,jslaby@xxxxxxx,lucas.de.marchi@xxxxxxxxx,mzxreary@xxxxxxxxxxx,nhorman@xxxxxxxxxxxxx,vda.linux@xxxxxxxxxxxxxx,walters@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 24 May 2013 12:53:45 -0700
The patch titled
Subject: coredump: cn_vprintf() has no reason to call vsnprintf() twice
has been added to the -mm tree. Its filename is
coredump-cn_vprintf-has-no-reason-to-call-vsnprintf-twice.patch
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From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: coredump: cn_vprintf() has no reason to call vsnprintf() twice
cn_vprintf() looks really overcomplicated and sub-optimal. We do not need
vsnprintf(NULL) to calculate the size we need, we can simply try to print
into the current buffer and expand/retry only if necessary.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Colin Walters <walters@xxxxxxxxxx>
Cc: Denys Vlasenko <vda.linux@xxxxxxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Cc: Lennart Poettering <mzxreary@xxxxxxxxxxx>
Cc: Lucas De Marchi <lucas.de.marchi@xxxxxxxxx>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/coredump.c | 28 +++++++++++-----------------
1 file changed, 11 insertions(+), 17 deletions(-)
diff -puN fs/coredump.c~coredump-cn_vprintf-has-no-reason-to-call-vsnprintf-twice fs/coredump.c
--- a/fs/coredump.c~coredump-cn_vprintf-has-no-reason-to-call-vsnprintf-twice
+++ a/fs/coredump.c
@@ -71,26 +71,20 @@ static int expand_corename(struct core_n
static int cn_vprintf(struct core_name *cn, const char *fmt, va_list arg)
{
- char *cur;
- int need;
- int ret;
+ int free, need;
- need = vsnprintf(NULL, 0, fmt, arg);
- if (likely(need < cn->size - cn->used - 1))
- goto out_printf;
+again:
+ free = cn->size - cn->used;
+ need = vsnprintf(cn->corename + cn->used, free, fmt, arg);
+ if (need < free) {
+ cn->used += need;
+ return 0;
+ }
- ret = expand_corename(cn);
- if (ret)
- goto expand_fail;
+ if (!expand_corename(cn))
+ goto again;
-out_printf:
- cur = cn->corename + cn->used;
- vsnprintf(cur, need + 1, fmt, arg);
- cn->used += need;
- return 0;
-
-expand_fail:
- return ret;
+ return -ENOMEM;
}
static int cn_printf(struct core_name *cn, const char *fmt, ...)
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
posix_cpu_timer-consolidate-expiry-time-type.patch
posix_cpu_timers-consolidate-timer-list-cleanups.patch
posix_cpu_timers-consolidate-expired-timers-check.patch
posix-timers-correctly-get-dying-task-time-sample-in-posix_cpu_timer_schedule.patch
posix_timers-fix-racy-timer-delta-caching-on-task-exit.patch
lockdep-introduce-lock_acquire_exclusive-shared-helper-macros.patch
lglock-update-lockdep-annotations-to-report-recursive-local-locks.patch
autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch
autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch
ptrace-x86-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-powerpc-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-arm-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-sh-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints.patch
ptrace-x86-simplify-the-disable-logic-in-ptrace_write_dr7.patch
ptrace-x86-dont-delay-disable-till-second-pass-in-ptrace_write_dr7.patch
ptrace-x86-introduce-ptrace_register_breakpoint.patch
ptrace-x86-ptrace_write_dr7-should-create-bp-if-disabled.patch
ptrace-x86-cleanup-ptrace_set_debugreg.patch
ptrace-ptrace_detach-should-do-flush_ptrace_hw_breakpointchild.patch
ptrace-x86-flush_ptrace_hw_breakpoint-shoule-clear-the-virtual-debug-registers.patch
x86-kill-tif_debug.patch
coredump-format_corename-can-leak-cn-corename.patch
coredump-introduce-cn_vprintf.patch
coredump-cn_vprintf-has-no-reason-to-call-vsnprintf-twice.patch
coredump-kill-cn_escape-introduce-cn_esc_printf.patch
coredump-kill-call_count-add-core_name_size.patch
coredump-%-at-the-end-shouldnt-bypass-core_uses_pid-logic.patch
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