Messages in this thread Patch in this message | | | From | Rusty Russell <> | Subject | [PATCH] Booting when CPUs fail to come up. | Date | Fri, 13 Feb 2004 18:57:03 +1100 |
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I recently played with setting a bit in cpu_possible_map that wasn't in cpu_online_map: this can happen without hotplug CPU when a CPU fails to boot, for example.
1) i386 should use cpu_callin_map for num_booting_cpus() (an x86-ism anyway): if a CPU doesn't come up, it will be set in cpu_possible_map (aka cpu_callout_map) but not cpu_callin_map.
2) When the cpu fails to come up, some callbacks do kthread_stop(), which doesn't work without keventd (which hasn't started yet). Call it directly, and take care that it restores signal state (note: do_sigaction does a flush on blocked signals, so we don't need to repeat it).
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .13580-linux-2.6.3-rc2-mm1/arch/i386/kernel/smpboot.c .13580-linux-2.6.3-rc2-mm1.updated/arch/i386/kernel/smpboot.c --- .13580-linux-2.6.3-rc2-mm1/arch/i386/kernel/smpboot.c 2004-02-13 17:28:16.000000000 +1100 +++ .13580-linux-2.6.3-rc2-mm1.updated/arch/i386/kernel/smpboot.c 2004-02-13 17:28:17.000000000 +1100 @@ -67,7 +67,7 @@ int smp_num_siblings = 1; int phys_proc_id[NR_CPUS]; /* Package ID of each logical CPU */ -static cpumask_t cpu_callin_map; +cpumask_t cpu_callin_map; cpumask_t cpu_callout_map; static cpumask_t smp_commenced_mask; diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .13580-linux-2.6.3-rc2-mm1/include/asm-i386/smp.h .13580-linux-2.6.3-rc2-mm1.updated/include/asm-i386/smp.h --- .13580-linux-2.6.3-rc2-mm1/include/asm-i386/smp.h 2004-02-13 17:28:15.000000000 +1100 +++ .13580-linux-2.6.3-rc2-mm1.updated/include/asm-i386/smp.h 2004-02-13 17:28:17.000000000 +1100 @@ -58,7 +58,8 @@ extern cpumask_t cpu_callout_map; /* We don't mark CPUs online until __cpu_up(), so we need another measure */ static inline int num_booting_cpus(void) { - return cpus_weight(cpu_callout_map); + extern cpumask_t cpu_callin_map; + return cpus_weight(cpu_callin_map); } extern void map_cpu_to_logical_apicid(void); diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .13580-linux-2.6.3-rc2-mm1/kernel/kthread.c .13580-linux-2.6.3-rc2-mm1.updated/kernel/kthread.c --- .13580-linux-2.6.3-rc2-mm1/kernel/kthread.c 2004-02-13 17:28:12.000000000 +1100 +++ .13580-linux-2.6.3-rc2-mm1.updated/kernel/kthread.c 2004-02-13 17:32:05.000000000 +1100 @@ -100,15 +100,16 @@ static void keventd_stop_kthread(void *_ { struct kthread_stop_info *stop = _stop; int status, pid; - sigset_t blocked; - struct k_sigaction sa; + sigset_t chldonly, oldset; + struct k_sigaction sa, oldsa; /* Install a handler so SIGCHLD is actually delivered */ sa.sa.sa_handler = SIG_DFL; sa.sa.sa_flags = 0; siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD)); - do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0); - allow_signal(SIGCHLD); + siginitset(&chldonly, sigmask(SIGCHLD)); + do_sigaction(SIGCHLD, &sa, &oldsa); + sigprocmask(SIG_UNBLOCK, &chldonly, &oldset); adopt_kthread(stop->k); /* Grab pid now: after waitpid(), stop->k is invalid. */ @@ -123,12 +124,9 @@ static void keventd_stop_kthread(void *_ stop->result = -((status >> 8) & 0xFF); complete(&stop->done); - /* Back to normal: block and flush all signals */ - sigfillset(&blocked); - sigprocmask(SIG_BLOCK, &blocked, NULL); - flush_signals(current); - sa.sa.sa_handler = SIG_IGN; - do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0); + /* Return to normal, then reap any children who died in the race. */ + sigprocmask(SIG_SETMASK, &oldset, NULL); + do_sigaction(SIGCHLD, &oldsa, NULL); while (waitpid(-1, &status, __WALL|WNOHANG) > 0); } @@ -179,7 +177,12 @@ int kthread_stop(struct task_struct *k) stop.k = k; init_completion(&stop.done); - schedule_work(&work); - wait_for_completion(&stop.done); + /* At boot, if CPUs fail to come up, this happens. */ + if (!keventd_up()) + work.func(work.data); + else { + schedule_work(&work); + wait_for_completion(&stop.done); + } return stop.result; } -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - 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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