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Tue, 03 Mar 2026 14:46:38 -0800 (PST) Date: Tue, 3 Mar 2026 14:46:36 -0800 From: Joe Damato To: Jakub Kicinski Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org Subject: Re: [PATCH net 4/5] nfc: nci: clear NCI_DATA_EXCHANGE before calling completion callback Message-ID: Mail-Followup-To: Joe Damato , Jakub Kicinski , davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org References: <20260303162346.2071888-1-kuba@kernel.org> <20260303162346.2071888-5-kuba@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260303162346.2071888-5-kuba@kernel.org> On Tue, Mar 03, 2026 at 08:23:44AM -0800, Jakub Kicinski wrote: > Move clear_bit(NCI_DATA_EXCHANGE) before invoking the data exchange > callback in nci_data_exchange_complete(). > > The callback (e.g. rawsock_data_exchange_complete) may immediately > schedule another data exchange via schedule_work(tx_work). On a > multi-CPU system, tx_work can run and reach nci_transceive() before > the current nci_data_exchange_complete() clears the flag, causing > test_and_set_bit(NCI_DATA_EXCHANGE) to return -EBUSY and the new > transfer to fail. > > This causes intermittent flakes in nci/nci_dev in NIPA: > > # # RUN NCI.NCI1_0.t4t_tag_read ... > # # t4t_tag_read: Test terminated by timeout > # # FAIL NCI.NCI1_0.t4t_tag_read > # not ok 3 NCI.NCI1_0.t4t_tag_read > > Fixes: 38f04c6b1b68 ("NFC: protect nci_data_exchange transactions") > Signed-off-by: Jakub Kicinski > --- > net/nfc/nci/data.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) Reviewed-by: Joe Damato