Re: [PATCH] pstore: Fix printing of duplicate boot messages to console
From: Kees Cook <hidden>
Date: 2020-01-27 23:27:36
Also in:
linux-arm-msm, lkml
On Thu, Jan 23, 2020 at 09:30:31PM +0530, Sai Prakash Ranjan wrote:
Since commit f92b070f2dc8 ("printk: Do not miss new messages
when replaying the log"), CON_PRINTBUFFER flag causes the
duplicate boot messages to be printed on the console when
PSTORE_CONSOLE and earlycon (boot console) is enabled.
Pstore console registers to boot console when earlycon is
enabled during pstore_register_console as a part of ramoops
initialization in postcore_initcall and the printk core
checks for CON_PRINTBUFFER flag and replays the log buffer
to registered console (in this case pstore console which
just registered to boot console) causing duplicate messages
to be printed. Remove the CON_PRINTBUFFER flag from pstore
console since pstore is not concerned with the printing of
buffer to console but with writing of the buffer to the
backend.I agree this patch isn't the solution, but I'm trying to understand where better logic could be added. Is the issue that printk sees both earlycon and CON_PRINTBUFFER active? Can we add a new CON_* flag that means "not actually printing anything"? (Or maybe a new flag for non-printing to replace CON_PRINTBUFFER that lets pstore still work?) -Kees
quoted hunk ↗ jump to hunk
Console log with earlycon and pstore console enabled: [ 0.008342] Console: colour dummy device 80x25 [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x51df805e] ... [ 1.244049] hw-breakpoint: found 6 breakpoint and 4 watchpoint registers. [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x51df805e] Fixes: f92b070f2dc8 ("printk: Do not miss new messages when replaying the log") Reported-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Sai Prakash Ranjan <redacted> --- fs/pstore/platform.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index d896457e7c11..271b00db0973 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c@@ -505,7 +505,7 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c) static struct console pstore_console = { .name = "pstore", .write = pstore_console_write, - .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME, + .flags = CON_ENABLED | CON_ANYTIME, .index = -1, };-- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
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