diff options
| author | Peng Zhang <zhangpeng.00@bytedance.com> | 2026-02-24 15:16:39 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-03-12 17:30:30 +0300 |
| commit | 24b98e8664e157aff0814a0f49895ee8223f382f (patch) | |
| tree | 4e1bd3be68b64de13f39b85724e3b23e73be1106 | |
| parent | a424a34b8faddf97b5af41689087e7a230f79ba7 (diff) | |
| download | linux-24b98e8664e157aff0814a0f49895ee8223f382f.tar.xz | |
serial: 8250: always disable IRQ during THRE test
commit 039d4926379b ("serial: 8250: Toggle IER bits on only after irq
has been set up") moved IRQ setup before the THRE test, in combination
with commit 205d300aea75 ("serial: 8250: change lock order in
serial8250_do_startup()") the interrupt handler can run during the
test and race with its IIR reads. This can produce wrong THRE test
results and cause spurious registration of the
serial8250_backup_timeout timer. Unconditionally disable the IRQ for
the short duration of the test and re-enable it afterwards to avoid
the race.
Fixes: 039d4926379b ("serial: 8250: Toggle IER bits on only after irq has been set up")
Depends-on: 205d300aea75 ("serial: 8250: change lock order in serial8250_do_startup()")
Cc: stable <stable@kernel.org>
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Alban Bedel <alban.bedel@lht.dlh.de>
Tested-by: Maximilian Lueer <maximilian.lueer@lht.dlh.de>
Link: https://patch.msgid.link/20260224121639.579404-1-alban.bedel@lht.dlh.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index cc94af2d578a..a743964c9d22 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2147,8 +2147,7 @@ static void serial8250_THRE_test(struct uart_port *port) if (up->port.flags & UPF_NO_THRE_TEST) return; - if (port->irqflags & IRQF_SHARED) - disable_irq_nosync(port->irq); + disable_irq(port->irq); /* * Test for UARTs that do not reassert THRE when the transmitter is idle and the interrupt @@ -2170,8 +2169,7 @@ static void serial8250_THRE_test(struct uart_port *port) serial_port_out(port, UART_IER, 0); } - if (port->irqflags & IRQF_SHARED) - enable_irq(port->irq); + enable_irq(port->irq); /* * If the interrupt is not reasserted, or we otherwise don't trust the iir, setup a timer to |