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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html