From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga07-in.huawei.com (szxga07-in.huawei.com [45.249.212.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D4610253331; Tue, 11 Mar 2025 11:41:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.35 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741693267; cv=none; b=Yw+l83Ep+MXp3IvAGuaJhl1C+NIhXbXSyph8ILYhnBfba3K1Prerk9DbbsfHouKeBYEOpyLBgzY9zBF5UGzVcp3PtRb7+bKLDhb6NGKMiCMEqrdU/NccPXle9e8XZni1VpwZTY3p/eBihKF2Z5U7p5WLHZHKVQf5Dn1va7JcfvI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741693267; c=relaxed/simple; bh=pJOG8csIWPPDOfgQc+UAEgcctcr7SDhTkMAIsGK9jNw=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=EhaqeHVcj0BJOg6aVoGGSZKf6nExPS84ydHLTpC935ze33FtQlHsySaq1NjqedeuIhVczCht3NsEphUuSbt25WzMMfWqZGy+wVy8fk0YPe0TJHX72Z06ZHJVuBxJqoqjflB7MMZc/frCZJyCtPKUrMfOWxo95xz9W1bGQ5ZLD8g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.35 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.162.112]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4ZBsD216QDz1f07m; Tue, 11 Mar 2025 19:36:34 +0800 (CST) Received: from dggemv703-chm.china.huawei.com (unknown [10.3.19.46]) by mail.maildlp.com (Postfix) with ESMTPS id 1B3FD140158; Tue, 11 Mar 2025 19:40:55 +0800 (CST) Received: from kwepemn100009.china.huawei.com (7.202.194.112) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Tue, 11 Mar 2025 19:40:54 +0800 Received: from [10.67.121.59] (10.67.121.59) by kwepemn100009.china.huawei.com (7.202.194.112) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 11 Mar 2025 19:40:54 +0800 Message-ID: <4ecf3a7a-7a68-fd56-ed93-fbae82e2b0e3@huawei.com> Date: Tue, 11 Mar 2025 19:40:53 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v2 01/13] mailbox: pcc: Fix the possible race in updation of chan_in_use flag To: Sudeep Holla , , CC: Jassi Brar , Adam Young , Robbie King References: <20250305-pcc_fixes_updates-v2-0-1b1822bc8746@arm.com> <20250305-pcc_fixes_updates-v2-1-1b1822bc8746@arm.com> From: "lihuisong (C)" In-Reply-To: <20250305-pcc_fixes_updates-v2-1-1b1822bc8746@arm.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemn100009.china.huawei.com (7.202.194.112) 在 2025/3/6 0:38, Sudeep Holla 写道: > From: Huisong Li > > The function mbox_chan_received_data() calls the Rx callback of the > mailbox client driver. The callback might set chan_in_use flag from > pcc_send_data(). This flag's status determines whether the PCC channel > is in use. > > However, there is a potential race condition where chan_in_use is > updated incorrectly due to concurrency between the interrupt handler > (pcc_mbox_irq()) and the command sender(pcc_send_data()). > > The 'chan_in_use' flag of a channel is set to true after sending a > command. And the flag of the new command may be cleared erroneous by > the interrupt handler afer mbox_chan_received_data() returns, > > As a result, the interrupt being level triggered can't be cleared in > pcc_mbox_irq() and it will be disabled after the number of handled times > exceeds the specified value. The error log is as follows: > > | kunpeng_hccs HISI04B2:00: PCC command executed timeout! > | kunpeng_hccs HISI04B2:00: get port link status info failed, ret = -110 > | irq 13: nobody cared (try booting with the "irqpoll" option) > | Call trace: > | dump_backtrace+0x0/0x210 > | show_stack+0x1c/0x2c > | dump_stack+0xec/0x130 > | __report_bad_irq+0x50/0x190 > | note_interrupt+0x1e4/0x260 > | handle_irq_event+0x144/0x17c > | handle_fasteoi_irq+0xd0/0x240 > | __handle_domain_irq+0x80/0xf0 > | gic_handle_irq+0x74/0x2d0 > | el1_irq+0xbc/0x140 > | mnt_clone_write+0x0/0x70 > | file_update_time+0xcc/0x160 > | fault_dirty_shared_page+0xe8/0x150 > | do_shared_fault+0x80/0x1d0 > | do_fault+0x118/0x1a4 > | handle_pte_fault+0x154/0x230 > | __handle_mm_fault+0x1ac/0x390 > | handle_mm_fault+0xf0/0x250 > | do_page_fault+0x184/0x454 > | do_translation_fault+0xac/0xd4 > | do_mem_abort+0x44/0xb4 > | el0_da+0x40/0x74 > | el0_sync_handler+0x60/0xb4 > | el0_sync+0x168/0x180 > | handlers: > | pcc_mbox_irq > | Disabling IRQ #13 > > To solve this issue, pcc_mbox_irq() must clear 'chan_in_use' flag before > the call to mbox_chan_received_data(). > > Signed-off-by: Huisong Li > (sudeep.holla: Minor updates to the subject and commit message) > Signed-off-by: Sudeep Holla > --- > drivers/mailbox/pcc.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c > index 82102a4c5d68839170238540a6fed61afa5185a0..f2e4087281c70eeb5b9b33371596613a371dff4f 100644 > --- a/drivers/mailbox/pcc.c > +++ b/drivers/mailbox/pcc.c > @@ -333,10 +333,15 @@ static irqreturn_t pcc_mbox_irq(int irq, void *p) > if (pcc_chan_reg_read_modify_write(&pchan->plat_irq_ack)) > return IRQ_NONE; > > + /* > + * Clear this flag immediately after updating interrupt ack register > + * to avoid possible race in updatation of the flag from > + * pcc_send_data() that could execute from mbox_chan_received_data() This comment may be inappropriate becuase of the moving of clearing interrupt ack register in patch 2/13. I suggested that fix it in this patch or patch 2/13. > + */ > + pchan->chan_in_use = false; > mbox_chan_received_data(chan, NULL); > > check_and_ack(pchan, chan); > - pchan->chan_in_use = false; > > return IRQ_HANDLED; > } >