linux/arch/um
Johannes Berg d5a9597d69 um: line: Use separate IRQs per line
Today, all possible serial lines (ssl*=) as well as all
possible consoles (con*=) each share a single interrupt
(with a fixed number) with others of the same type.

Now, if you have two lines, say ssl0 and ssl1, and one
of them is connected to an fd you cannot read (e.g. a
file), but the other gets a read interrupt, then both
of them get the interrupt since it's shared. Then, the
read() call will return EOF, since it's a file being
written and there's nothing to read (at least not at
the current offset, at the end).

Unfortunately, this is treated as a read error, and we
close this line, losing all the possible output.

It might be possible to work around this and make the
IRQ sharing work, however, now that we have dynamically
allocated IRQs that are easy to use, simply use that to
achieve separating between the events; then there's no
interrupt for that line and we never attempt the read
in the first place, thus not closing the line.

This manifested itself in the wifi hostap/hwsim tests
where the parallel script communicates via one serial
console and the kernel messages go to another (a file)
and sending data on the communication console caused
the kernel messages to stop flowing into the file.

Reported-by: Jouni Malinen <j@w1.fi>
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>
2022-05-27 09:03:41 +02:00
..
configs kunit: Move default config from arch/um -> tools/testing/kunit 2021-06-23 17:49:17 -06:00
drivers um: line: Use separate IRQs per line 2022-05-27 09:03:41 +02:00
include um: line: Use separate IRQs per line 2022-05-27 09:03:41 +02:00
kernel This pull request contains the following changes for UML: 2022-03-31 16:16:58 -07:00
os-Linux This pull request contains the following changes for UML: 2022-03-31 16:16:58 -07:00
scripts License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
.gitignore um: gitignore: Add kernel/capflags.c 2021-12-21 21:22:43 +01:00
Kbuild kbuild: require all architectures to have arch/$(SRCARCH)/Kbuild 2021-05-26 23:10:37 +09:00
Kconfig um: Enable ARCH_HAS_GCOV_PROFILE_ALL 2022-05-27 09:01:14 +02:00
Kconfig.debug um: Disable CONFIG_GCOV with MODULES 2021-04-15 23:10:33 +02:00
Makefile Revert "um: clang: Strip out -mno-global-merge from USER_CFLAGS" 2022-04-02 00:05:28 +09:00
Makefile-os-Linux
Makefile-skas