Hi,
On 19-07-18 10:53, Petr Mladek wrote:
On Wed 2018-07-18 11:30:02, Thomas Zimmermann wrote:
If the console is unlocked during registration, the console subsystem
generates significant amounts of warnings, which obfuscate actual
debugging messages. Setting ignore_console_lock_warning while debugging
console registration avoid the noise.
v2:
- restore ignore_console_lock_warning if lock_fb_info() fails
Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
---
drivers/video/fbdev/core/fbmem.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 9e2f9d3c760e..432c26eeabfb 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1627,6 +1627,7 @@ static int do_register_framebuffer(struct fb_info
*fb_info)
int i, ret;
struct fb_event event;
struct fb_videomode mode;
+ bool saved_ignore_console_lock_warning = ignore_console_lock_warning;
Hmm, this approach is racy if there are other users
saving/setting/restoring ignore_console_lock_warning in parallel.
I mean that this works only when the entire safe/set/restore
operation is nested or sequential.
We might need another approach if there are more users,
e.g. use an atomic counter for ignore_console_lock_warning.
I noticed this would be racy too, but this only gets used when
console-locking should be disabled when registering fbdev-s
for debugging purposes at which point everything console related
is racy already anyways, so I think this is fine as is.
On the other hand, I wonder if there ever will be other user.
Also it is "just" for debugging. We could keep it simple for now.
It might be enough to add a comment into include/linux/console.h,
something like:
Ack, lets keep this simple / as is in v2 of the patch.
Regards,
Hans
/*
* Set ignore_console_lock_warning to true if you need to quiet
* WARN_CONSOLE_UNLOCKED() for debugging purposes. Might need
* another approach if manipulated by more users in parallel.
*/
Best Regards,
Petr
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