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[77.7.18.194]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47f63eddd1csm19863025f8f.29.2026.07.19.03.28.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Jul 2026 03:28:14 -0700 (PDT) Date: Sun, 19 Jul 2026 12:27:41 +0200 From: Karl Mehltretter To: sashiko-reviews@lists.linux.dev Cc: linux-rt-devel@lists.linux.dev, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Subject: Re: [PATCH 1/2] serial: amba-pl011: unprepare console clock on unregister Message-ID: References: <20260719063502.18852-1-kmehltretter@gmail.com> <20260719063502.18852-2-kmehltretter@gmail.com> <20260719070454.D6FA21F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260719070454.D6FA21F000E9@smtp.kernel.org> On Sun, Jul 19, 2026 at 07:04:54AM +0100, sashiko-bot@kernel.org wrote: > This is a pre-existing issue, but does uap need a NULL check here to > prevent a kernel panic on error paths? > > If uart_add_one_port() fails internally (e.g., an allocation failure in > serial_core_add_one_port() returning -ENOMEM), it returns an error but > crucially fails to unregister the console that was already registered > earlier in uart_configure_port(). > > The caller sees the error and clears the pointer: > > drivers/tty/serial/amba-pl011.c:pl011_register_port() { > ... > ret = uart_add_one_port(&amba_reg, &uap->port); > if (ret) > pl011_unregister_port(uap); Good catch in a rare error path. A NULL check alone is not enough because other callbacks use the same pointer. The underlying issue is that serial core can leave the console registered after uart_add_one_port() fails. I will investigate that separately. Karl