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Tue, 02 Jun 2026 21:02:49 -0700 (PDT) From: Rosen Penev To: linux-watchdog@vger.kernel.org Cc: Wim Van Sebroeck , Guenter Roeck , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v2 1/2] watchdog: pika_wdt: fix timer leak and close race Date: Tue, 2 Jun 2026 21:02:29 -0700 Message-ID: <20260603040230.318998-2-rosenp@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260603040230.318998-1-rosenp@gmail.com> References: <20260603040230.318998-1-rosenp@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Two timer lifecycle bugs in the PIKA watchdog driver: 1. pikawdt_exit() unmaps the FPGA IO memory without stopping the ping timer. A timer tick after iounmap executes pikawdt_ping() on freed memory. Add timer_delete_sync() before iounmap. 2. pikawdt_release() uses timer_delete() which does not synchronize with a concurrently executing timer handler. If pikawdt_ping() runs on another CPU after timer_delete() marks the timer as deleted but before the open bit is cleared, it can call mod_timer() and re-arm itself. Once the open bit is subsequently cleared, the condition (!nowayout && !open) becomes true and the timer keeps patting the watchdog forever, defeating the intended reset-on-unexpected-close. Fix by clearing the open bit before calling timer_delete_sync(), which waits for any in-flight handler to complete. Assisted-by: opencode:big-pickle Signed-off-by: Rosen Penev --- drivers/watchdog/pika_wdt.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/watchdog/pika_wdt.c b/drivers/watchdog/pika_wdt.c index 87b8988d2520..60a846cb3601 100644 --- a/drivers/watchdog/pika_wdt.c +++ b/drivers/watchdog/pika_wdt.c @@ -127,11 +127,12 @@ static int pikawdt_open(struct inode *inode, struct f= ile *file) */ static int pikawdt_release(struct inode *inode, struct file *file) { + clear_bit(0, &pikawdt_private.open); + /* stop internal ping */ if (!pikawdt_private.expect_close) - timer_delete(&pikawdt_private.timer); + timer_delete_sync(&pikawdt_private.timer); =20 - clear_bit(0, &pikawdt_private.open); pikawdt_private.expect_close =3D 0; return 0; } @@ -291,6 +292,7 @@ static void __exit pikawdt_exit(void) { misc_deregister(&pikawdt_miscdev); =20 + timer_delete_sync(&pikawdt_private.timer); iounmap(pikawdt_private.fpga); } =20 --=20 2.54.0 From nobody Mon Jun 8 06:36:45 2026 Received: from mail-qk1-f180.google.com (mail-qk1-f180.google.com [209.85.222.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 391183F54C3 for ; 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Tue, 02 Jun 2026 21:02:53 -0700 (PDT) Received: from ryzen ([2601:644:8000:5b5d:7285:c2ff:fe45:8a32]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9158a3eea49sm127604285a.44.2026.06.02.21.02.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Jun 2026 21:02:51 -0700 (PDT) From: Rosen Penev To: linux-watchdog@vger.kernel.org Cc: Wim Van Sebroeck , Guenter Roeck , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v2 2/2] watchdog: pika_wdt: replace in_be32/out_be32 with ioread32be/iowrite32be Date: Tue, 2 Jun 2026 21:02:30 -0700 Message-ID: <20260603040230.318998-3-rosenp@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260603040230.318998-1-rosenp@gmail.com> References: <20260603040230.318998-1-rosenp@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Convert the ppc4xx-specific in_be32/out_be32 to the portable ioread32be/iowrite32be. Also relax the Kconfig dependency from (PPC64 && COMPILE_TEST) to just COMPILE_TEST to get build coverage. Add HAS_IOMEM dependency for these functions. Assisted-by: opencode:big-pickle Signed-off-by: Rosen Penev --- drivers/watchdog/Kconfig | 3 ++- drivers/watchdog/pika_wdt.c | 8 ++++---- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index 8319c503319a..855736eaca2c 100644 --- a/drivers/watchdog/Kconfig +++ b/drivers/watchdog/Kconfig @@ -2040,7 +2040,8 @@ config 8xxx_WDT =20 config PIKA_WDT tristate "PIKA FPGA Watchdog" - depends on WARP || (PPC64 && COMPILE_TEST) + depends on WARP || COMPILE_TEST + depends on HAS_IOMEM default WARP help This enables the watchdog in the PIKA FPGA. Currently used on diff --git a/drivers/watchdog/pika_wdt.c b/drivers/watchdog/pika_wdt.c index 60a846cb3601..beb3ba1ab84f 100644 --- a/drivers/watchdog/pika_wdt.c +++ b/drivers/watchdog/pika_wdt.c @@ -77,10 +77,10 @@ static inline void pikawdt_reset(void) * seconds. Valid ranges are 1 to 15 seconds. The value can * be modified dynamically. */ - unsigned reset =3D in_be32(pikawdt_private.fpga + 0x14); + unsigned reset =3D ioread32be(pikawdt_private.fpga + 0x14); /* enable with max timeout - 15 seconds */ reset |=3D (1 << 7) + (WDT_HW_TIMEOUT << 8); - out_be32(pikawdt_private.fpga + 0x14, reset); + iowrite32be(reset, pikawdt_private.fpga + 0x14); } =20 /* @@ -243,7 +243,7 @@ static int __init pikawdt_init(void) return -ENOMEM; } =20 - ident.firmware_version =3D in_be32(pikawdt_private.fpga + 0x1c) & 0xffff; + ident.firmware_version =3D ioread32be(pikawdt_private.fpga + 0x1c) & 0xff= ff; =20 /* POST information is in the sd area. */ np =3D of_find_compatible_node(NULL, NULL, "pika,fpga-sd"); @@ -265,7 +265,7 @@ static int __init pikawdt_init(void) * Bit 31, WDOG: Set to 1 when the last reset was caused by a watchdog * timeout. */ - post1 =3D in_be32(fpga + 0x40); + post1 =3D ioread32be(fpga + 0x40); if (post1 & 0x80000000) pikawdt_private.bootstatus =3D WDIOF_CARDRESET; =20 --=20 2.54.0