[PATCH 3/8] PM: suspend_block: Abort task freezing if a suspend_blocker is active.
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From: Arve Hjønnevåg on 28 Apr 2010 00:40 If a suspend_blocker is active, suspend will fail anyway. Since try_to_freeze_tasks can take up to 20 seconds to complete or fail, aborting as soon as someone blocks suspend (e.g. from an interrupt handler) improves the worst case wakeup latency. On an older kernel where task freezing could fail for processes attached to a debugger, this fixed a problem where the device sometimes hung for 20 seconds before the screen turned on. Signed-off-by: Arve Hjønnevåg <arve(a)android.com> --- kernel/power/process.c | 12 ++++++++++-- 1 files changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/power/process.c b/kernel/power/process.c index 71ae290..d8ebd50 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -15,6 +15,7 @@ #include <linux/syscalls.h> #include <linux/freezer.h> #include <linux/delay.h> +#include <linux/suspend_blocker.h> /* * Timeout for stopping processes @@ -38,6 +39,7 @@ static int try_to_freeze_tasks(bool sig_only) struct timeval start, end; u64 elapsed_csecs64; unsigned int elapsed_csecs; + bool wakeup = false; do_gettimeofday(&start); @@ -63,6 +65,10 @@ static int try_to_freeze_tasks(bool sig_only) todo++; } while_each_thread(g, p); read_unlock(&tasklist_lock); + if (todo && suspend_is_blocked()) { + wakeup = true; + break; + } if (!todo || time_after(jiffies, end_time)) break; @@ -85,13 +91,15 @@ static int try_to_freeze_tasks(bool sig_only) * but it cleans up leftover PF_FREEZE requests. */ printk("\n"); - printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds " + printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds " "(%d tasks refusing to freeze):\n", + wakeup ? "aborted" : "failed", elapsed_csecs / 100, elapsed_csecs % 100, todo); read_lock(&tasklist_lock); do_each_thread(g, p) { task_lock(p); - if (freezing(p) && !freezer_should_skip(p)) + if (freezing(p) && !freezer_should_skip(p) + && elapsed_csecs > 100) sched_show_task(p); cancel_freezing(p); task_unlock(p); -- 1.6.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |