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([2001:a61:1363:9e01:43f1:e533:276c:e9a1]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4851fad27dbsm31071765e9.2.2026.03.05.03.35.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Mar 2026 03:35:54 -0800 (PST) Message-ID: Date: Thu, 5 Mar 2026 12:35:53 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [BUG] usb: cdc-wdm: Missing barriers in ad-hoc lockless buffer To: Gui-Dong Han , Greg KH , oneukum@suse.com Cc: robert.hodaszi@digi.com, kees@kernel.org, linux-usb@vger.kernel.org, LKML , Jia-Ju Bai References: Content-Language: en-US From: Oliver Neukum In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04.03.26 09:41, Gui-Dong Han wrote: > Additionally, the driver relies heavily on set_bit() and test_bit() on > desc->flags for synchronization. These bit operations do not provide > implicit barriers, which might lead to similar ordering issues. Hi, going through the driver it seems to me like all relevant cases are covered by the iuspin spinlock. Do you have any concrete suspicions or do you generally distrust this style? Regards Oliver