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Thu, 23 Jul 2020 00:19:41 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id C802BC43391; Thu, 23 Jul 2020 00:19:40 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: tingwei) by smtp.codeaurora.org (Postfix) with ESMTPSA id 4AF56C433C6; Thu, 23 Jul 2020 00:19:40 +0000 (UTC) MIME-Version: 1.0 Date: Thu, 23 Jul 2020 08:19:40 +0800 From: tingwei@codeaurora.org To: Suzuki K Poulose Subject: Re: [PATCH v3 19/20] coresight: add try_get_module() in coresight_grab_device() In-Reply-To: <34a3a704-293c-54ac-edfa-17715f419fa4@arm.com> References: <20200717054536.7052-1-tingwei@codeaurora.org> <20200717054536.7052-20-tingwei@codeaurora.org> <7ef8d427-23c9-10cd-b337-03ae75476a8c@arm.com> <34a3a704-293c-54ac-edfa-17715f419fa4@arm.com> Message-ID: X-Sender: tingwei@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200722_202020_878309_B718040F X-CRM114-Status: GOOD ( 13.21 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tsoni@codeaurora.org, saiprakash.ranjan@codeaurora.org, kim.phillips@arm.com, mathieu.poirier@linaro.org, alexander.shishkin@linux.intel.com, gregkh@linuxfoundation.org, coresight@lists.linaro.org, rdunlap@infradead.org, ykaukab@suse.de, linux@armlinux.org.uk, jinlmao@codeaurora.org, leo.yan@linaro.org, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-07-22 18:51, Suzuki K Poulose wrote: > On 07/22/2020 11:49 AM, Suzuki K Poulose wrote: >> Hi Tingwei, >> >> On 07/17/2020 06:45 AM, Tingwei Zhang wrote: >>> When coresight device is in an active session, driver module of >>> that device should not be removed. Use try_get_module() in >>> coresight_grab_device() to prevent module to be unloaded. >>> >> >> Is this really sufficient ? AFAIU, a device could be removed, but the >> module may still be alive due to the refcount on the module. This >> could imply that we have stale pointers in the _path_, which could >> lead to corruption elsewhere. Should we do a get/put_device() instead >> ? > > Also, logically this refcount solution patch must be applied before > the drivers are made modules to prevent breaking bisection failures. > So, please re-order the patches in the series to take that into > consideration. > > Suzuki That's good point. I'll reorder them in next revision. Thanks, Tingwei _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel