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Wed, 10 Dec 2025 07:12:55 -0800 (PST) Received: from pathway ([176.114.240.130]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42f9f5ab46csm10337308f8f.19.2025.12.10.07.12.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Dec 2025 07:12:55 -0800 (PST) Date: Wed, 10 Dec 2025 16:12:53 +0100 From: Petr Mladek To: Chris Down Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Sergey Senozhatsky , Steven Rostedt , John Ogness , Geert Uytterhoeven , Tony Lindgren , kernel-team@fb.com Subject: Re: [PATCH v8 06/21] printk: nbcon: Synchronise console unregistration against atomic flushers Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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