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Commit3ed1cfb
speakup ttyio: Do not schedule() in ttyio_in_nowait
With the ltlk and spkout drivers, the index read function, i.e.in_nowait, is getting called from the read_all_doc mechanism, fromthe timer softirq:Call Trace: <IRQ> dump_stack+0x71/0x98 dequeue_task_idle+0x1f/0x28 __schedule+0x167/0x5d6 ? trace_hardirqs_on+0x2e/0x3a ? usleep_range+0x7f/0x7f schedule+0x8a/0xae schedule_timeout+0xb1/0xea ? del_timer_sync+0x31/0x31 do_wait_for_common+0xba/0x12b ? wake_up_q+0x45/0x45 wait_for_common+0x37/0x50 ttyio_in+0x2a/0x6b spk_ttyio_in_nowait+0xc/0x13 spk_get_index_count+0x20/0x93 cursor_done+0x1c6/0x4c6 ? read_all_doc+0xb1/0xb1 call_timer_fn+0x89/0x140 run_timer_softirq+0x164/0x1a5 ? read_all_doc+0xb1/0xb1 ? hrtimer_forward+0x7b/0x87 ? timerqueue_add+0x62/0x68 ? enqueue_hrtimer+0x95/0x9f __do_softirq+0x181/0x31f irq_exit+0x6a/0x86smp_apic_timer_interrupt+0x15e/0x183 apic_timer_interrupt+0xf/0x20 </IRQ>We thus should not schedule() at all, even with timeout == 0, thiscrashes the kernel. We can however use try_wait_for_completion()instead of wait_for_completion_timeout(0).Cc: stable@vger.kernel.orgReported-by: John Covici <covici@ccs.covici.com>Tested-by: John Covici <covici@ccs.covici.com>Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>Link:https://lore.kernel.org/r/20201108131233.tadycr73sxlvodgo@functionSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>1 parent640969a commit3ed1cfb
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