From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793974924; b=DaT1UG9YXj3+YC6wOH+AzD22RSIFyX4E1430gDKI/0Kl6guiglVEAH1iriVU0WLQjoRr E2ZSRrWcKhzTQbYETaFh23p0SLbR9+xHXEHWrsItPsibxb7CbxYC/GH9lciYmyzw810jJ aeeioUqxgDAFaVb+5WAvjMQSjnX1XIQe1lon9JFnby94NsCQ5t1wNopNh1RTa47REN5oF 3Q+SG5BCAJ58dx9M1DdLYxMpvbhzeDLN/Sr4JrfNQxZ93b1+D6QD5gUIXb39d6uFzNXNX RNXzMQqrC305jK72Qfemi/3kt1Ff8eH0o1RfyL8MPbKMogAwZO/xnGmUZMrEk+ACrCg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793974924; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=1CyuNBbmHWfQlK02spGsrvL05FvW7QnAOT3CvHmfiNE=; b=V0XjzrnDCv5PrW53+hb7akSvmd50/mpazKWiq/7P6Zl31SpPxfRFTfGXB4j9qliR4+6h G/hSJs/zeDFwl7AgD0CQCYzI1zGwjRI8nKFs87WotibgyFSMQ8Y2I/+goQNUjHExMZTbh MCBrZCI9av4KCOYG7p1S7OWkXFCp0pLbO6BJZTbBlwoDPTqXl+c8gyLkZt+OVucwtxhJR sl5xGS+eod+IDedGQSXE3BnvDP3WyoIrdbdYH4Dnz7+XGKwwZB14s4ntcsD5Ip3SMB3hM YTDD+7ljy6ZfcKjv/4UPRBjC/nRZW6vaAzMUMCpAHW7cMoLqKFLAHgFJQXc2NmK8prA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=IHMt8wMz; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E33B1606A32C for ; Fri, 6 Nov 2026 14:22:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=IHMt8wMz Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCCE71F0089F; Fri, 6 Nov 2026 14:22:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793974923; bh=1CyuNBbmHWfQlK02spGsrvL05FvW7QnAOT3CvHmfiNE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=IHMt8wMzhXIUe7GP8kcFGGsoScQlFkbez6kHIzAQ69khNj++niP5n1FLJ98d071RH Pohfzh147bB3lIE22uLxgTvd8tsaj6Y+YXTy8Mt0p+k8Zuo1iltTpJKwRudVcl8l2f 3T+5ieUi/zDLGL4b57abTOgwZbihQLTQNbHU6xRDhQCNw6aa4NA6v4RUlt6DOruaqC w/VPg8ydScbtP5mwAt5rxYFUh+v+r8J01V8tofPwzNkOmuGDNXcMOQis25PpqV/Ub+ DILDogBICf2cDc68kAcWn2IuYXrVJ18dMWfsfaj6YvaZr+6wL1tbHNnvfY0wievqc2 Cm2bUFTl5i5Tg== Date: Fri, 6 Nov 2026 14:22:01 +0000 From: Tzung-Bi Shih To: Guenter Roeck Cc: linux-watchdog@vger.kernel.org, Xingyu Wu , Ziv Xu Subject: Re: [PATCH v2 6/8] watchdog: starfive-wdt: Avoid unclocked MMIO read in starfive_wdt_get_timeleft() Message-ID: References: <20261105190530.2371854-1-linux@roeck-us.net> <20261105190530.2371854-7-linux@roeck-us.net> X-Mailing-List: linux-watchdog@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261105190530.2371854-7-linux@roeck-us.net> On Thu, Nov 05, 2026 at 11:05:27AM -0800, Guenter Roeck wrote: > When the watchdog is inactive, runtime PM suspends the device and gates > off apb_clk and core_clk via starfive_wdt_runtime_suspend(). However, > reading the sysfs timeleft attribute via timeleft_show() or issuing > ioctl(WDIOC_GETTIMELEFT) calls starfive_wdt_get_timeleft() unconditionally. > > Because starfive_wdt_get_timeleft() reads the counter and interrupt status > registers without checking whether the hardware watchdog is running, > querying timeleft while inactive performs unclocked MMIO reads and triggers > a bus fault. > > Return 0 immediately in starfive_wdt_get_timeleft() when > watchdog_hw_running() is false. When watchdog_hw_running() is true, the > driver holds an active runtime PM reference keeping the clocks enabled. > > Fixes: db728ea9c7be ("drivers: watchdog: Add StarFive Watchdog driver") > Cc: Xingyu Wu > Cc: Ziv Xu > Signed-off-by: Guenter Roeck Reviewed-by: Tzung-Bi Shih