From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: - xtime_lock-vs-update_process_times.patch removed from -mm tree Date: Thu, 14 Feb 2008 14:23:44 -0500 Message-ID: <200802150227.m1F2R34m015285@imap1.linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:53136 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758686AbYBOC3l (ORCPT ); Thu, 14 Feb 2008 21:29:41 -0500 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: a.p.zijlstra@chello.nl, bryan.wu@analog.com, dhowells@redhat.com, gerg@uclinux.org, ink@jurassic.park.msu.ru, lethal@linux-sh.org, mingo@elte.hu, rth@twiddle.net, tglx@linutronix.de The patch titled xtime_lock vs update_process_times has been removed from the -mm tree. Its filename was xtime_lock-vs-update_process_times.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: xtime_lock vs update_process_times From: Peter Zijlstra Commit: d3d74453c34f8fd87674a8cf5b8a327c68f22e99 Subject: hrtimer: fixup the HRTIMER_CB_IRQSAFE_NO_SOFTIRQ fallback Broke several archs. I have confirmation that the Alpha bit results in a booting kernel. That leaves: blackfin, frv, sh and sparc untested. The deadlock in question was found by Russell: IRQ handle -> timer_tick() - xtime seqlock held for write -> update_process_times() -> run_local_timers() -> hrtimer_run_queues() -> hrtimer_get_softirq_time() - tries to get a read lock Now, Thomas assures me the fix is trivial, only do_timer() needs to be done under the xtime_lock, and update_process_times() can savely be removed from under it. Signed-off-by: Peter Zijlstra Acked-by: Greg Ungerer Cc: Richard Henderson Tested-by: Ivan Kokshaysky Cc: Bryan Wu Cc: David Howells Cc: Paul Mundt Cc: William Lee Irwin III Cc: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- arch/alpha/kernel/time.c | 15 ++++++++------- arch/blackfin/kernel/time.c | 8 +++++--- arch/frv/kernel/time.c | 6 ++++-- arch/m68knommu/kernel/time.c | 12 +++++++----- arch/sparc/kernel/pcic.c | 2 +- arch/sparc/kernel/time.c | 7 +++---- 6 files changed, 28 insertions(+), 22 deletions(-) diff -puN arch/alpha/kernel/time.c~xtime_lock-vs-update_process_times arch/alpha/kernel/time.c --- a/arch/alpha/kernel/time.c~xtime_lock-vs-update_process_times +++ a/arch/alpha/kernel/time.c @@ -119,13 +119,8 @@ irqreturn_t timer_interrupt(int irq, voi state.partial_tick = delta & ((1UL << FIX_SHIFT) - 1); nticks = delta >> FIX_SHIFT; - while (nticks > 0) { - do_timer(1); -#ifndef CONFIG_SMP - update_process_times(user_mode(get_irq_regs())); -#endif - nticks--; - } + if (nticks) + do_timer(nticks); /* * If we have an externally synchronized Linux clock, then update @@ -141,6 +136,12 @@ irqreturn_t timer_interrupt(int irq, voi } write_sequnlock(&xtime_lock); + +#ifndef CONFIG_SMP + while (nticks--) + update_process_times(user_mode(get_irq_regs())); +#endif + return IRQ_HANDLED; } diff -puN arch/blackfin/kernel/time.c~xtime_lock-vs-update_process_times arch/blackfin/kernel/time.c --- a/arch/blackfin/kernel/time.c~xtime_lock-vs-update_process_times +++ a/arch/blackfin/kernel/time.c @@ -137,9 +137,6 @@ irqreturn_t timer_interrupt(int irq, voi do_timer(1); -#ifndef CONFIG_SMP - update_process_times(user_mode(get_irq_regs())); -#endif profile_tick(CPU_PROFILING); /* @@ -161,6 +158,11 @@ irqreturn_t timer_interrupt(int irq, voi last_rtc_update = xtime.tv_sec - 600; } write_sequnlock(&xtime_lock); + +#ifndef CONFIG_SMP + update_process_times(user_mode(get_irq_regs())); +#endif + return IRQ_HANDLED; } diff -puN arch/frv/kernel/time.c~xtime_lock-vs-update_process_times arch/frv/kernel/time.c --- a/arch/frv/kernel/time.c~xtime_lock-vs-update_process_times +++ a/arch/frv/kernel/time.c @@ -63,6 +63,7 @@ static irqreturn_t timer_interrupt(int i /* last time the cmos clock got updated */ static long last_rtc_update = 0; + profile_tick(CPU_PROFILING); /* * Here we are in the timer irq handler. We just have irqs locally * disabled but we don't know if the timer_bh is running on the other @@ -73,8 +74,6 @@ static irqreturn_t timer_interrupt(int i write_seqlock(&xtime_lock); do_timer(1); - update_process_times(user_mode(get_irq_regs())); - profile_tick(CPU_PROFILING); /* * If we have an externally synchronized Linux clock, then update @@ -99,6 +98,9 @@ static irqreturn_t timer_interrupt(int i #endif /* CONFIG_HEARTBEAT */ write_sequnlock(&xtime_lock); + + update_process_times(user_mode(get_irq_regs())); + return IRQ_HANDLED; } diff -puN arch/m68knommu/kernel/time.c~xtime_lock-vs-update_process_times arch/m68knommu/kernel/time.c --- a/arch/m68knommu/kernel/time.c~xtime_lock-vs-update_process_times +++ a/arch/m68knommu/kernel/time.c @@ -42,14 +42,12 @@ irqreturn_t arch_timer_interrupt(int irq /* last time the cmos clock got updated */ static long last_rtc_update=0; + if (current->pid) + profile_tick(CPU_PROFILING); + write_seqlock(&xtime_lock); do_timer(1); -#ifndef CONFIG_SMP - update_process_times(user_mode(get_irq_regs())); -#endif - if (current->pid) - profile_tick(CPU_PROFILING); /* * If we have an externally synchronized Linux clock, then update @@ -67,6 +65,10 @@ irqreturn_t arch_timer_interrupt(int irq } write_sequnlock(&xtime_lock); + +#ifndef CONFIG_SMP + update_process_times(user_mode(get_irq_regs())); +#endif return(IRQ_HANDLED); } diff -puN arch/sparc/kernel/pcic.c~xtime_lock-vs-update_process_times arch/sparc/kernel/pcic.c --- a/arch/sparc/kernel/pcic.c~xtime_lock-vs-update_process_times +++ a/arch/sparc/kernel/pcic.c @@ -713,10 +713,10 @@ static irqreturn_t pcic_timer_handler (i write_seqlock(&xtime_lock); /* Dummy, to show that we remember */ pcic_clear_clock_irq(); do_timer(1); + write_sequnlock(&xtime_lock); #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); #endif - write_sequnlock(&xtime_lock); return IRQ_HANDLED; } diff -puN arch/sparc/kernel/time.c~xtime_lock-vs-update_process_times arch/sparc/kernel/time.c --- a/arch/sparc/kernel/time.c~xtime_lock-vs-update_process_times +++ a/arch/sparc/kernel/time.c @@ -128,10 +128,6 @@ irqreturn_t timer_interrupt(int irq, voi clear_clock_irq(); do_timer(1); -#ifndef CONFIG_SMP - update_process_times(user_mode(get_irq_regs())); -#endif - /* Determine when to update the Mostek clock. */ if (ntp_synced() && @@ -145,6 +141,9 @@ irqreturn_t timer_interrupt(int irq, voi } write_sequnlock(&xtime_lock); +#ifndef CONFIG_SMP + update_process_times(user_mode(get_irq_regs())); +#endif return IRQ_HANDLED; } _ Patches currently in -mm which might be from a.p.zijlstra@chello.nl are origin.patch softlockup-workaround.patch git-sched.patch git-sh.patch proc-add-rlimit_rttime-to-proc-pid-limits.patch taint-kernel-after-warn_oncondition.patch mm-bdi-export-bdi-attributes-in-sysfs.patch mm-bdi-expose-the-bdi-object-in-sysfs-for-nfs.patch mm-bdi-expose-the-bdi-object-in-sysfs-for-fuse.patch mm-bdi-allow-setting-a-minimum-for-the-bdi-dirty-limit.patch mm-bdi-allow-setting-a-maximum-for-the-bdi-dirty-limit.patch