Messages in this thread Patch in this message | | | From | Sumit Garg <> | Subject | [PATCH v2] kdb: Make kdb_printf robust to run in NMI context | Date | Fri, 22 May 2020 20:03:47 +0530 |
| |
While rounding up CPUs via NMIs, its possible that a rounded up CPU maybe holding a console port lock leading to kgdb master CPU stuck in a deadlock during invocation of console write operations. So in order to avoid such a deadlock, invoke bust_spinlocks() prior to invocation of console handlers.
Also, add a check for console port to be enabled prior to invocation of corresponding handler.
Suggested-by: Petr Mladek <pmladek@suse.com> Suggested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Sumit Garg <sumit.garg@linaro.org> ---
Changes in v2: - Use oops_in_progress directly instead of bust_spinlocks().
kernel/debug/kdb/kdb_io.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c index 924bc92..3a5a068 100644 --- a/kernel/debug/kdb/kdb_io.c +++ b/kernel/debug/kdb/kdb_io.c @@ -699,7 +699,11 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap) } } for_each_console(c) { + if (!(c->flags & CON_ENABLED)) + continue; + ++oops_in_progress; c->write(c, cp, retlen - (cp - kdb_buffer)); + --oops_in_progress; touch_nmi_watchdog(); } } @@ -761,7 +765,11 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap) } } for_each_console(c) { + if (!(c->flags & CON_ENABLED)) + continue; + ++oops_in_progress; c->write(c, moreprompt, strlen(moreprompt)); + --oops_in_progress; touch_nmi_watchdog(); } -- 2.7.4
| |