media: rc: sir_ir: detect presence of port

Browse source

commit 30b4e122d7 upstream.

Without this test, sir_ir clumsy claims resources for a device which
does not exist.

The 0-day kernel test robot reports the following errors (in a loop):
	sir_ir sir_ir.0: Trapped in interrupt
	genirq: Flags mismatch irq 4. 00000000 (ttyS0) vs. 00000000 (sir_ir)

When sir_ir is loaded with the default io and irq, the following happens:
 - sir_ir claims irq 4
 - user space opens /dev/ttyS0
 - in serial8250_do_startup(), some setup is done for ttyS0, which causes
   irq 4 to fire (in THRE test)
 - sir_ir does not realise it was not for it, and spins until the "trapped
   in interrupt"
 - now serial driver calls setup_irq() and fails and we get the
   "Flags mismatch" error.

There is no port present at 0x3e8 so simply check for the presence of a
port, as suggested by Linus.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Sean Young 2017-11-08 16:19:45 -05:00 • committed by Greg Kroah-Hartman

parent 9a11204d2b

commit 2f2241083a

1 changed files with 36 additions and 4 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

40

drivers/media/rc/sir_ir.c

View file