diff options
| author | John Ogness <john.ogness@linutronix.de> | 2022-11-16 17:27:19 +0106 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2022-12-02 11:24:59 +0100 |
| commit | 3860e7c57fd23e744e045436f9872fb9d01381e2 (patch) | |
| tree | 1e3b1edbb9eff00d99f8ad6a37d2bbcd3b8a5cdc /arch/um/kernel | |
| parent | a42427609368d773c4ab6b4c9686577817a4d219 (diff) | |
| download | linux-3860e7c57fd23e744e045436f9872fb9d01381e2.tar.bz2 | |
um: kmsg_dump: only dump when no output console available
The initial intention of the UML kmsg_dumper is to dump the kernel
buffers to stdout if there is no console available to perform the
regular crash output.
However, if ttynull was registered as a console, no crash output was
seen. Commit e23fe90dec28 ("um: kmsg_dumper: always dump when not tty
console") tried to fix this by performing the kmsg_dump unless the
stdio console was behind /dev/console or enabled. But this allowed
kmsg dumping to occur even if other non-stdio consoles will output
the crash output. Also, a console being the driver behind
/dev/console has nothing to do with a crash scenario.
Restore the initial intention by dumping the kernel buffers to stdout
only if a non-ttynull console is registered and enabled. Also add
detailed comments so that it is clear why these rules are applied.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-8-john.ogness@linutronix.de
Diffstat (limited to 'arch/um/kernel')
| -rw-r--r-- | arch/um/kernel/kmsg_dump.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c index 0224fcb36e22..40abf1e9ccb1 100644 --- a/arch/um/kernel/kmsg_dump.c +++ b/arch/um/kernel/kmsg_dump.c @@ -17,13 +17,22 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper, unsigned long flags; size_t len = 0; - /* only dump kmsg when no console is available */ + /* + * If no consoles are available to output crash information, dump + * the kmsg buffer to stdout. + */ + if (!console_trylock()) return; for_each_console(con) { - if(strcmp(con->name, "tty") == 0 && - (con->flags & (CON_ENABLED | CON_CONSDEV)) != 0) { + /* + * The ttynull console and disabled consoles are ignored + * since they cannot output. All other consoles are + * expected to output the crash information. + */ + if (strcmp(con->name, "ttynull") != 0 && + (con->flags & CON_ENABLED)) { break; } } |