From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id BD6671CDA0B; Tue, 11 Mar 2025 12:02:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741694543; cv=none; b=OqmA2BQIqHXVh6KNwky8N/til2U6PpOXGPiopKCngzj4l1KTSvYVGL2/lPz0z5R98zWct4/tXKrdi0iAO18axpnuOjMQUz7FMwCTjABREOoDh9tH9RhNgEvMRG7UEUtGIDPOLr0qLoy302st2ju5fM7fTrmNu0hH070wY/AwqEA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741694543; c=relaxed/simple; bh=Bmb2tzliIGNBiIX24m2PDco4gc9/BfA6OUhbq+dpSK8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LTAma+qrh6XZl4MzEQj889iEiVTzp60svKnmgthXq4mKKN1K4ICGHURW1QD+qffQbvJWL2Iss4v1q2sSjcSztHqXoDfshgNO3kHipxlW7nBz+N3DxGlqqNkeqFt7lgDW/BsQSSAkqRFx/15YwhBzoLS5b8mCodCkwbRw8KJEMEs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 05937152B; Tue, 11 Mar 2025 05:02:32 -0700 (PDT) Received: from bogus (e133711.arm.com [10.1.196.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B40943F673; Tue, 11 Mar 2025 05:02:19 -0700 (PDT) Date: Tue, 11 Mar 2025 12:02:16 +0000 From: Sudeep Holla To: "lihuisong (C)" Cc: , , Jassi Brar , Adam Young , Robbie King Subject: Re: [PATCH v2 01/13] mailbox: pcc: Fix the possible race in updation of chan_in_use flag Message-ID: References: <20250305-pcc_fixes_updates-v2-0-1b1822bc8746@arm.com> <20250305-pcc_fixes_updates-v2-1-1b1822bc8746@arm.com> <4ecf3a7a-7a68-fd56-ed93-fbae82e2b0e3@huawei.com> Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4ecf3a7a-7a68-fd56-ed93-fbae82e2b0e3@huawei.com> On Tue, Mar 11, 2025 at 07:40:53PM +0800, lihuisong (C) wrote: > > 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. Right, I did think of updating or did update and missed to commit. I wanted to update something like: " Clear this flag after updating interrupt ack register and just before mbox_chan_received_data() which might call pcc_send_data() where the flag is set again to start new transfer " Hope that is more apt to the current situation. -- Regards, Sudeep