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Sat, 05 Sep 2026 12:29:27 -0700 (PDT) From: Matt Turner Date: Sat, 05 Sep 2026 15:29:22 -0400 Subject: [PATCH v2 01/22] alpha: enter hardirq context before looking up the irq descriptor 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="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260905-arch-kconfig-options-v2-v2-1-83e8245761a2@gmail.com> References: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> In-Reply-To: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> To: Richard Henderson , Magnus Lindholm , Kees Cook , Marco Elver , Andrey Konovalov , Andrey Ryabinin , Jonathan Corbet , Shuah Khan , Randy Dunlap Cc: linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org, Matt Turner X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1372; i=mattst88@gmail.com; h=from:subject:message-id; bh=ipd5upR2TEicpga1iLZip+mHEfDMT1WpKFPSlKGjSaY=; b=owGbwMvMwCW25rVmCc8sv+mMp9WSGLLm5E4+t2kl9wXTxDXhVofZ2/30lDO/v3/bsz10jojH+ gu+n59mdnxkYRDjYpgppsgSt16RZVbbjqU+p6V/wcxhZQIZIi3SwAAELAx8uYl5pUY6Rnqm2oZ6 hkCGjlE8RE6PQSOzuLg0tUg3raDIIS+/JLEkMz+vWC+/IDWvIL1ALy0zrSQjI7+oOBVohF5eaom pq6ObkaGBiaWjhZmThaOpibOzk6GTm6Ojs6uTkaW5iYGzpaOJq6U5AxenAMw1sw0Z/mkUZfEcPl 6Um9Okxx7ucbu/ffGSzHQnZcdr1b+fyXUwmzMybLxgkGgl2lTmobr02SHJE4dNu9K2sV7fxHlj6 v0ewedr2QA= X-Developer-Key: i=mattst88@gmail.com; a=openpgp; fpr=3BB639E56F861FA2E86505690FDD682D974CA72A handle_irq() called irq_to_desc() before irq_enter(), so that lookup ran with the preempt count still saying task context and with RCU not yet watching. Generic code called from an interrupt handler should see hardirq context, and irq_to_desc() is more than an array index once SPARSE_IRQ is in use. Move irq_enter() to the top of the function and add the matching irq_exit() to the invalid interrupt path. Assisted-by: Claude:claude-opus-5 Signed-off-by: Matt Turner --- arch/alpha/kernel/irq.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/alpha/kernel/irq.c b/arch/alpha/kernel/irq.c index 4a6a8b1d5a8b..5867a1655045 100644 --- a/arch/alpha/kernel/irq.c +++ b/arch/alpha/kernel/irq.c @@ -107,18 +107,21 @@ handle_irq(int irq) * handled by some other CPU. (or is disabled) */ static unsigned int illegal_count=0; - struct irq_desc *desc = irq_to_desc(irq); - + struct irq_desc *desc; + + irq_enter(); + + desc = irq_to_desc(irq); if (!desc || ((unsigned) irq > ACTUAL_NR_IRQS && illegal_count < MAX_ILLEGAL_IRQS)) { irq_err_count++; illegal_count++; printk(KERN_CRIT "device_interrupt: invalid interrupt %d\n", irq); + irq_exit(); return; } - irq_enter(); generic_handle_irq_desc(desc); irq_exit(); } -- 2.54.0