From: Petr Mladek <pmladek@suse.com>
To: Chris Down <chris@chrisdown.name>
Cc: linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
John Ogness <john.ogness@linutronix.de>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Tony Lindgren <tony.lindgren@linux.intel.com>,
kernel-team@fb.com
Subject: Re: [PATCH v8 06/21] printk: nbcon: Synchronise console unregistration against atomic flushers
Date: Wed, 10 Dec 2025 16:12:53 +0100 [thread overview]
Message-ID: <aTmN9fUiJt5gm6Vq@pathway> (raw)
In-Reply-To: <e763af8ab34d96fcd02e76ad7b41f6b95c78850a.1764272407.git.chris@chrisdown.name>
On Fri 2025-11-28 03:43:32, Chris Down wrote:
> The nbcon atomic flush path in __nbcon_atomic_flush_pending_con() calls
> nbcon_emit_next_record(), which uses console_srcu_read_flags() to read
> the console flags. console_srcu_read_flags() expects to be called under
> console_srcu_read_lock(), but the atomic flush path does not hold this
> lock.
__nbcon_atomic_flush_pending_con() seems to be called in the following
code paths:
+ __nbcon_atomic_flush_pending()
+ nbcon_atomic_flush_pending_con()
+ __nbcon_atomic_flush_pending_con()
+ nbcon_device_release()
+ __nbcon_atomic_flush_pending_con()
+ kdb_msg_write() # new in 6.19-rc1
+ nbcon_kdb_release()
+ __nbcon_atomic_flush_pending_con()
And all three callers take console_srcu_read_lock() because
they need it for other reasons. So, we should be on the safe
side and do not need this change.
Or do I miss some code path, please?
Best Regards,
Petr
next prev parent reply other threads:[~2025-12-10 15:12 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-27 19:43 [PATCH v8 00/21] printk: console: Per-console loglevels Chris Down
2025-11-27 19:43 ` [PATCH v8 01/21] printk: Fully resolve loglevel before deciding printk delay suppression Chris Down
2025-12-09 16:40 ` Petr Mladek
2025-12-11 14:49 ` Petr Mladek
2025-12-11 15:28 ` Petr Mladek
2025-11-27 19:43 ` [PATCH v8 02/21] printk: Avoid spuriously delaying messages not solicited by any console Chris Down
2025-11-27 19:43 ` [PATCH v8 03/21] printk: Prioritise user-specified configuration over SPCR/DT Chris Down
2025-12-10 14:38 ` Petr Mladek
2025-11-27 19:43 ` [PATCH v8 04/21] printk: Use effective loglevel for suppression and extended console state Chris Down
2025-11-27 19:43 ` [PATCH v8 05/21] printk: console: Add per-console loglevel support to struct console Chris Down
2025-11-27 19:43 ` [PATCH v8 06/21] printk: nbcon: Synchronise console unregistration against atomic flushers Chris Down
2025-12-10 15:12 ` Petr Mladek [this message]
2025-11-27 19:43 ` [PATCH v8 07/21] printk: Introduce per-console loglevel support Chris Down
2025-11-27 19:43 ` [PATCH v8 08/21] printk: Iterate registered consoles for delay suppression decisions Chris Down
2025-11-27 19:43 ` [PATCH v8 09/21] printk: Optimise printk_delay() to avoid walking consoles under SRCU Chris Down
2025-12-11 14:37 ` Petr Mladek
2025-11-27 19:43 ` [PATCH v8 10/21] printk: Add synchronisation for concurrent console state changes Chris Down
2025-11-27 19:43 ` [PATCH v8 11/21] printk: Add ignore_per_console_loglevel module parameter Chris Down
2025-11-27 19:43 ` [PATCH v8 12/21] printk: Ensure sysrq output bypasses per-console filtering Chris Down
2025-11-27 19:44 ` [PATCH v8 13/21] printk: Toggle ignore_per_console_loglevel via syslog Chris Down
2025-11-27 19:44 ` [PATCH v8 14/21] printk: console: Introduce sysfs interface for per-console loglevels Chris Down
2025-12-12 14:04 ` Petr Mladek
2025-11-27 19:44 ` [PATCH v8 15/21] printk: sysrq: Clamp console loglevel to valid range Chris Down
2025-12-12 14:10 ` Petr Mladek
2025-11-27 19:44 ` [PATCH v8 16/21] printk: Constrain hardware-addressed console checks to name position Chris Down
2025-11-27 19:44 ` [PATCH v8 17/21] printk: Support setting initial console loglevel via console= on cmdline Chris Down
2025-11-27 19:44 ` [PATCH v8 18/21] printk: Deconstruct kernel.printk into discrete sysctl controls Chris Down
2025-12-12 15:24 ` Petr Mladek
2025-12-15 10:08 ` Joel Granados
2025-12-15 16:09 ` Petr Mladek
2025-11-27 19:44 ` [PATCH v8 19/21] printk: docs: Add comprehensive guidance for per-console loglevels Chris Down
2025-12-12 15:32 ` Petr Mladek
2025-11-27 19:44 ` [PATCH v8 20/21] printk: Deprecate the kernel.printk sysctl interface Chris Down
2025-12-12 15:51 ` Petr Mladek
2025-12-15 9:52 ` Joel Granados
2025-12-15 16:06 ` Petr Mladek
2025-12-17 11:47 ` Joel Granados
2025-12-17 14:33 ` Geert Uytterhoeven
2025-12-17 16:04 ` Steven Rostedt
2025-12-17 20:23 ` Joel Granados
2025-11-27 19:44 ` [PATCH v8 21/21] printk: Purge default_console_loglevel Chris Down
2025-12-12 16:11 ` [PATCH v8 00/21] printk: console: Per-console loglevels Petr Mladek
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