Messages in this thread Patch in this message | | | Date | Thu, 08 Oct 2020 13:19:56 -0000 | From | "tip-bot2 for Kajol Jain" <> | Subject | [tip: perf/core] perf: Fix task_function_call() error handling |
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The following commit has been merged into the perf/core branch of tip:
Commit-ID: 84ad70320241566e028ada955c694ab92f3351e3 Gitweb: https://git.kernel.org/tip/84ad70320241566e028ada955c694ab92f3351e3 Author: Kajol Jain <kjain@linux.ibm.com> AuthorDate: Thu, 27 Aug 2020 12:17:32 +05:30 Committer: Peter Zijlstra <peterz@infradead.org> CommitterDate: Thu, 08 Oct 2020 15:16:29 +02:00
perf: Fix task_function_call() error handling
The error handling introduced by commit:
2ed6edd33a21 ("perf: Add cond_resched() to task_function_call()")
looses any return value from smp_call_function_single() that is not {0, -EINVAL}. This is a problem because it will return -EXNIO when the target CPU is offline. Worse, in that case it'll turn into an infinite loop.
Fixes: 2ed6edd33a21 ("perf: Add cond_resched() to task_function_call()") Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Kajol Jain <kjain@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Barret Rhoden <brho@google.com> Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: https://lkml.kernel.org/r/20200827064732.20860-1-kjain@linux.ibm.com --- kernel/events/core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 45edb85..85a6e7f 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -99,7 +99,7 @@ static void remote_function(void *data) * retry due to any failures in smp_call_function_single(), such as if the * task_cpu() goes offline concurrently. * - * returns @func return value or -ESRCH when the process isn't running + * returns @func return value or -ESRCH or -ENXIO when the process isn't running */ static int task_function_call(struct task_struct *p, remote_function_f func, void *info) @@ -115,7 +115,8 @@ task_function_call(struct task_struct *p, remote_function_f func, void *info) for (;;) { ret = smp_call_function_single(task_cpu(p), remote_function, &data, 1); - ret = !ret ? data.ret : -EAGAIN; + if (!ret) + ret = data.ret; if (ret != -EAGAIN) break;
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