Messages in this thread | | | Date | Tue, 2 Apr 2019 10:47:17 +0800 | From | Feng Tang <> | Subject | Re: [PATCH 1/2] printk: Add an option to flush all messages on panic |
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Hi Mukesh,
On Mon, Apr 01, 2019 at 05:20:33PM +0530, Mukesh Ojha wrote: > > On 4/1/2019 4:18 PM, Feng Tang wrote: > > Current console_flush_on_panic() will only dump the new messages > > in buffer, and users may need an opportunity to check all the > > messages on panic which could help debugging, as user may haven't > > seen the log before panic due to loglevel settings. > > > > Add a flag for console_flush_on_panic() to chose whether to > > dump all messages. > > > > Signed-off-by: Feng Tang <feng.tang@intel.com> > > > Looks good to me.
Thanks for the review.
> > > But, Will it not be good if put it under a config and not change the > prototype, as it is a debug feature?
My understanding is the console_flush_on_panic() is also a debug feature too :), and my 2/2 patch will has a bitmask (either controlled by kernel cmdline or sysctl) to turn on this.
Thanks, Feng
> > Thanks, > Mukesh > > > --- > > arch/powerpc/kernel/traps.c | 2 +- > > include/linux/console.h | 2 +- > > kernel/panic.c | 2 +- > > kernel/printk/printk.c | 9 ++++++++- > > 4 files changed, 11 insertions(+), 4 deletions(-) > > > > diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c > > index 1fd45a8..58d9580 100644 > > --- a/arch/powerpc/kernel/traps.c > > +++ b/arch/powerpc/kernel/traps.c > > @@ -179,7 +179,7 @@ extern void panic_flush_kmsg_end(void) > > kmsg_dump(KMSG_DUMP_PANIC); > > bust_spinlocks(0); > > debug_locks_off(); > > - console_flush_on_panic(); > > + console_flush_on_panic(false); > > } > > static unsigned long oops_begin(struct pt_regs *regs) > > diff --git a/include/linux/console.h b/include/linux/console.h > > index ec9bdb3..825ecf5 100644 > > --- a/include/linux/console.h > > +++ b/include/linux/console.h > > @@ -175,7 +175,7 @@ extern int console_trylock(void); > > extern void console_unlock(void); > > extern void console_conditional_schedule(void); > > extern void console_unblank(void); > > -extern void console_flush_on_panic(void); > > +extern void console_flush_on_panic(bool flush_all); > > extern struct tty_driver *console_device(int *); > > extern void console_stop(struct console *); > > extern void console_start(struct console *); > > diff --git a/kernel/panic.c b/kernel/panic.c > > index 0ae0d73..fb77e01 100644 > > --- a/kernel/panic.c > > +++ b/kernel/panic.c > > @@ -277,7 +277,7 @@ void panic(const char *fmt, ...) > > * panic() is not being callled from OOPS. > > */ > > debug_locks_off(); > > - console_flush_on_panic(); > > + console_flush_on_panic(false); > > panic_print_sys_info(); > > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > > index 02ca827..8ff099b 100644 > > --- a/kernel/printk/printk.c > > +++ b/kernel/printk/printk.c > > @@ -2525,10 +2525,11 @@ void console_unblank(void) > > /** > > * console_flush_on_panic - flush console content on panic > > + * @flush_all: whether to print all messages in buffer > > * > > * Immediately output all pending messages no matter what. > > */ > > -void console_flush_on_panic(void) > > +void console_flush_on_panic(bool flush_all) > > { > > /* > > * If someone else is holding the console lock, trylock will fail > > @@ -2539,6 +2540,12 @@ void console_flush_on_panic(void) > > */ > > console_trylock(); > > console_may_schedule = 0; > > + > > + /* User may want to see all the printk messages on panic */ > > + if (flush_all) { > > + console_seq = log_first_seq; > > + console_idx = log_first_idx; > > + } > > console_unlock(); > > }
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