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| author | Johannes Berg <johannes.berg@intel.com> | 2020-09-10 12:31:12 +0300 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2020-10-12 00:13:20 +0300 |
| commit | ebef8ea2ba967026192a26f4529890893919bc57 (patch) | |
| tree | 1af3fa2aeb094eb61b0709aa279696a469b213da /arch/um/kernel | |
| parent | 730586ff7fada525943f1eee0681fa62a3fc6128 (diff) | |
| download | linux-ebef8ea2ba967026192a26f4529890893919bc57.tar.xz | |
um: time-travel: Fix IRQ handling in time_travel_handle_message()
As the comment here indicates, we need to do the polling in the
idle loop without blocking interrupts, since interrupts can be
vhost-user messages that we must process even while in our idle
loop.
I don't know why I explained one thing and implemented another,
but we have indeed observed random hangs due to this, depending
on the timing of the messages.
Fixes: 88ce64249233 ("um: Implement time-travel=ext")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/kernel')
| -rw-r--r-- | arch/um/kernel/time.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c index 25eaa6a0c658..c07436e89e59 100644 --- a/arch/um/kernel/time.c +++ b/arch/um/kernel/time.c @@ -70,13 +70,17 @@ static void time_travel_handle_message(struct um_timetravel_msg *msg, * read of the message and write of the ACK. */ if (mode != TTMH_READ) { + bool disabled = irqs_disabled(); + + BUG_ON(mode == TTMH_IDLE && !disabled); + + if (disabled) + local_irq_enable(); while (os_poll(1, &time_travel_ext_fd) != 0) { - if (mode == TTMH_IDLE) { - BUG_ON(!irqs_disabled()); - local_irq_enable(); - local_irq_disable(); - } + /* nothing */ } + if (disabled) + local_irq_disable(); } ret = os_read_file(time_travel_ext_fd, msg, sizeof(*msg)); |