kernel/linux.git/include/linux/printk.h, branch v6.1.176

printk: add print_hex_dump_devel()

2026-06-19T11:37:20+00:00

[ Upstream commit d134feeb5df33fbf77f482f52a366a44642dba09 ] Add print_hex_dump_devel() as the hex dump equivalent of pr_devel(), which emits output only when DEBUG is enabled, but keeps call sites compiled otherwise. Suggested-by: Herbert Xu Signed-off-by: Thorsten Blum Reviewed-by: John Ogness Signed-off-by: Herbert Xu Stable-dep-of: 177730a273b1 ("crypto: caam - guard HMAC key hex dumps in hash_digest_key") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

lib/hexdump: print_hex_dump_bytes() calls print_hex_dump_debug()

2026-06-01T15:39:21+00:00

[ Upstream commit 36776b7f8a8955b4e75b5d490a75fee0c7a2a7ef ] print_hex_dump_bytes() claims to be a simple wrapper around print_hex_dump(), but it actally calls print_hex_dump_debug(), which means no output is printed if (dynamic) DEBUG is disabled. Update the documentation to match the implementation. Fixes: 091cb0994edd20d6 ("lib/hexdump: make print_hex_dump_bytes() a nop on !DEBUG builds") Signed-off-by: Geert Uytterhoeven Reviewed-by: Petr Mladek Link: https://patch.msgid.link/3d5c3069fd9102ecaf81d044b750cd613eb72a08.1774970392.git.geert+renesas@glider.be Signed-off-by: Petr Mladek Signed-off-by: Sasha Levin

printk: Let no_printk() use _printk()

2024-06-12T09:03:21+00:00

[ Upstream commit 8522f6b760ca588928eede740d5d69dd1e936b49 ] When printk-indexing is enabled, each printk() invocation emits a pi_entry structure, containing the format string and other information related to its location in the kernel sources. This is even true for no_printk(): while the actual code to print the message is optimized out by the compiler due to the always-false check, the pi_entry structure is still emitted. As the main purpose of no_printk() is to provide a helper to maintain printf()-style format checking when debugging is disabled, this leads to the inclusion in the index of lots of printk formats that cannot be emitted by the current kernel. Fix this by switching no_printk() from printk() to _printk(). This reduces the size of an arm64 defconfig kernel with CONFIG_PRINTK_INDEX=y by 576 KiB. Fixes: 337015573718b161 ("printk: Userspace format indexing support") Signed-off-by: Geert Uytterhoeven Reviewed-by: Andy Shevchenko Reviewed-by: Xiubo Li Reviewed-by: Chris Down Reviewed-by: Petr Mladek Link: https://lore.kernel.org/r/56cf92edccffea970e1f40a075334dd6cf5bb2a4.1709127473.git.geert+renesas@glider.be Signed-off-by: Petr Mladek Signed-off-by: Sasha Levin

Merge branch 'rework/kthreads' into for-linus

2022-10-04T13:55:55+00:00

printk: Make pr_flush() static

2022-09-29T13:20:22+00:00

No user outside the printk code and no reason to export this. Signed-off-by: Thomas Gleixner Signed-off-by: John Ogness Reviewed-by: Sergey Senozhatsky Reviewed-by: Petr Mladek Reviewed-by: Greg Kroah-Hartman Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220924000454.3319186-2-john.ogness@linutronix.de

Merge branch 'rework/kthreads' into for-linus

2022-06-23T17:11:28+00:00

Revert "printk: add functions to prefer direct printing"

2022-06-23T16:41:40+00:00

This reverts commit 2bb2b7b57f81255c13f4395ea911d6bdc70c9fe2. The testing of 5.19 release candidates revealed missing synchronization between early and regular console functionality. It would be possible to start the console kthreads later as a workaround. But it is clear that console lock serialized console drivers between each other. It opens a big area of possible problems that were not considered by people involved in the development and review. printk() is crucial for debugging kernel issues and console output is very important part of it. The number of consoles is huge and a proper review would take some time. As a result it need to be reverted for 5.19. Link: https://lore.kernel.org/r/YrBdjVwBOVgLfHyb@alley Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220623145157.21938-7-pmladek@suse.com

Revert "printk: Wait for the global console lock when the system is going down"

2022-06-23T16:41:40+00:00

This reverts commit b87f02307d3cfbda768520f0687c51ca77e14fc3. The testing of 5.19 release candidates revealed missing synchronization between early and regular console functionality. It would be possible to start the console kthreads later as a workaround. But it is clear that console lock serialized console drivers between each other. It opens a big area of possible problems that were not considered by people involved in the development and review. printk() is crucial for debugging kernel issues and console output is very important part of it. The number of consoles is huge and a proper review would take some time. As a result it need to be reverted for 5.19. Link: https://lore.kernel.org/r/YrBdjVwBOVgLfHyb@alley Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220623145157.21938-2-pmladek@suse.com

Merge branch 'rework/kthreads' into for-linus

2022-06-17T14:36:48+00:00

printk: Wait for the global console lock when the system is going down

2022-06-15T20:04:15+00:00

There are reports that the console kthreads block the global console lock when the system is going down, for example, reboot, panic. First part of the solution was to block kthreads in these problematic system states so they stopped handling newly added messages. Second part of the solution is to wait when for the kthreads when they are actively printing. It solves the problem when a message was printed before the system entered the problematic state and the kthreads managed to step in. A busy waiting has to be used because panic() can be called in any context and in an unknown state of the scheduler. There must be a timeout because the kthread might get stuck or sleeping and never release the lock. The timeout 10s is an arbitrary value inspired by the softlockup timeout. Link: https://lore.kernel.org/r/20220610205038.GA3050413@paulmck-ThinkPad-P17-Gen-1 Link: https://lore.kernel.org/r/CAMdYzYpF4FNTBPZsEFeWRuEwSies36QM_As8osPWZSr2q-viEA@mail.gmail.com Signed-off-by: Petr Mladek Tested-by: Paul E. McKenney Link: https://lore.kernel.org/r/20220615162805.27962-3-pmladek@suse.com