From 6fb86d97207880c1286cd4cb3a7e6a598afbc727 Mon Sep 17 00:00:00 2001 From: Mukesh Ojha Date: Tue, 28 Aug 2018 12:24:54 +0530 Subject: cpu/hotplug: Remove skip_onerr field from cpuhp_step structure When notifiers were there, `skip_onerr` was used to avoid calling particular step startup/teardown callbacks in the CPU up/down rollback path, which made the hotplug asymmetric. As notifiers are gone now after the full state machine conversion, the `skip_onerr` field is no longer required. Remove it from the structure and its usage. Signed-off-by: Mukesh Ojha Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/1535439294-31426-1-git-send-email-mojha@codeaurora.org --- kernel/cpu.c | 26 ++++---------------------- 1 file changed, 4 insertions(+), 22 deletions(-) (limited to 'kernel/cpu.c') diff --git a/kernel/cpu.c b/kernel/cpu.c index ed44d7d34c2d..aa7fe85ad62e 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -102,8 +102,6 @@ static inline void cpuhp_lock_release(bool bringup) { } * @name: Name of the step * @startup: Startup function of the step * @teardown: Teardown function of the step - * @skip_onerr: Do not invoke the functions on error rollback - * Will go away once the notifiers are gone * @cant_stop: Bringup/teardown can't be stopped at this step */ struct cpuhp_step { @@ -119,7 +117,6 @@ struct cpuhp_step { struct hlist_node *node); } teardown; struct hlist_head list; - bool skip_onerr; bool cant_stop; bool multi_instance; }; @@ -550,12 +547,8 @@ static int bringup_cpu(unsigned int cpu) static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st) { - for (st->state--; st->state > st->target; st->state--) { - struct cpuhp_step *step = cpuhp_get_step(st->state); - - if (!step->skip_onerr) - cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); - } + for (st->state--; st->state > st->target; st->state--) + cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); } static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, @@ -644,12 +637,6 @@ static void cpuhp_thread_fun(unsigned int cpu) WARN_ON_ONCE(!cpuhp_is_ap_state(state)); - if (st->rollback) { - struct cpuhp_step *step = cpuhp_get_step(state); - if (step->skip_onerr) - goto next; - } - if (cpuhp_is_atomic_state(state)) { local_irq_disable(); st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last); @@ -673,7 +660,6 @@ static void cpuhp_thread_fun(unsigned int cpu) st->should_run = false; } -next: cpuhp_lock_release(bringup); if (!st->should_run) @@ -916,12 +902,8 @@ void cpuhp_report_idle_dead(void) static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st) { - for (st->state++; st->state < st->target; st->state++) { - struct cpuhp_step *step = cpuhp_get_step(st->state); - - if (!step->skip_onerr) - cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); - } + for (st->state++; st->state < st->target; st->state++) + cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); } static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, -- cgit v1.2.3 From f8b7530aa0a1def79c93101216b5b17cf408a70a Mon Sep 17 00:00:00 2001 From: Neeraj Upadhyay Date: Wed, 5 Sep 2018 11:22:07 +0530 Subject: cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun() The smp_mb() in cpuhp_thread_fun() is misplaced. It needs to be after the load of st->should_run to prevent reordering of the later load/stores w.r.t. the load of st->should_run. Fixes: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core") Signed-off-by: Neeraj Upadhyay Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Cc: josh@joshtriplett.org Cc: peterz@infradead.org Cc: jiangshanlai@gmail.com Cc: dzickus@redhat.com Cc: brendan.jackman@arm.com Cc: malat@debian.org Cc: mojha@codeaurora.org Cc: sramana@codeaurora.org Cc: linux-arm-msm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1536126727-11629-1-git-send-email-neeraju@codeaurora.org --- kernel/cpu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/cpu.c') diff --git a/kernel/cpu.c b/kernel/cpu.c index aa7fe85ad62e..eb4041f78073 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -607,15 +607,15 @@ static void cpuhp_thread_fun(unsigned int cpu) bool bringup = st->bringup; enum cpuhp_state state; + if (WARN_ON_ONCE(!st->should_run)) + return; + /* * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures * that if we see ->should_run we also see the rest of the state. */ smp_mb(); - if (WARN_ON_ONCE(!st->should_run)) - return; - cpuhp_lock_acquire(bringup); if (st->single) { -- cgit v1.2.3 From 69fa6eb7d6a64801ea261025cce9723d9442d773 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 6 Sep 2018 15:21:38 +0200 Subject: cpu/hotplug: Prevent state corruption on error rollback When a teardown callback fails, the CPU hotplug code brings the CPU back to the previous state. The previous state becomes the new target state. The rollback happens in undo_cpu_down() which increments the state unconditionally even if the state is already the same as the target. As a consequence the next CPU hotplug operation will start at the wrong state. This is easily to observe when __cpu_disable() fails. Prevent the unconditional undo by checking the state vs. target before incrementing state and fix up the consequently wrong conditional in the unplug code which handles the failure of the final CPU take down on the control CPU side. Fixes: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core") Reported-by: Neeraj Upadhyay Signed-off-by: Thomas Gleixner Tested-by: Geert Uytterhoeven Tested-by: Sudeep Holla Tested-by: Neeraj Upadhyay Cc: josh@joshtriplett.org Cc: peterz@infradead.org Cc: jiangshanlai@gmail.com Cc: dzickus@redhat.com Cc: brendan.jackman@arm.com Cc: malat@debian.org Cc: sramana@codeaurora.org Cc: linux-arm-msm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1809051419580.1416@nanos.tec.linutronix.de ---- --- kernel/cpu.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel/cpu.c') diff --git a/kernel/cpu.c b/kernel/cpu.c index eb4041f78073..0097acec1c71 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -916,7 +916,8 @@ static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); if (ret) { st->target = prev_state; - undo_cpu_down(cpu, st); + if (st->state < prev_state) + undo_cpu_down(cpu, st); break; } } @@ -969,7 +970,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, * to do the further cleanups. */ ret = cpuhp_down_callbacks(cpu, st, target); - if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) { + if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) { cpuhp_reset_state(st, prev_state); __cpuhp_kick_ap(st); } -- cgit v1.2.3