From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.3]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 003D88827 for ; Fri, 12 Jul 2024 02:49:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.3 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720752575; cv=none; b=W1aeE+wAwo2UqceBPpuhQhfjwdN0HgPKyTLdSgo7TChKgVXCACBzzuQKBWM2qmFplwnBkPjZjTi/Ld8s8fiO0gy6nJg9/yUqOiYOFtY0PmWFzdWPQqJES9uqB4Qtbq9MWnlH7X63cjCaBM6LOsBBoghFlcJxIL3NUTIKYSKa34g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720752575; c=relaxed/simple; bh=S57/KDq7P5Qt3wR3elqgGqliTx6bQ1P+tjGuNGv3hVk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Lx4wUcNSXMPK81wCB6dy/JjjzC5i+Ob1Qt2nKBOEfKq3rTENDj+ZhJgssnu7OcIxbSC+lenV1FwICSSO5KD9qr0Teji41p9Nasyp18NpyVhWMI/UWqUhKjrchX3oHO9I3F7HNcKfCPpXNf0i740uBptCIF+lxRyfcKeDECp/rHY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=DgtKMlG5; arc=none smtp.client-ip=220.197.31.3 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="DgtKMlG5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=Date:From:Subject:Message-ID:MIME-Version: Content-Type; bh=hpC7v1EFyxVgnyXWRHFU602gKIYNOFAAowQgLZKdJRw=; b=DgtKMlG53e4b8m3Qk4SIEJpO/3qqBpBZdsBPJWjtbhfoRGS0uD36wGFB/B+o4P beNtKcLQdQlpppJ+3eah+kLqzxjX2ZvbgQX/1Es2VbrHM1ugKLmEfC3WKDiqjbSU aSv7x7HevgrJ3+6xWKQlHykZXFeLZ06X1ldRsRkH4ZqtM= Received: from localhost (unknown [125.33.20.250]) by gzga-smtp-mta-g2-5 (Coremail) with SMTP id _____wDnDzfqmJBmKWHIAA--.747S2; Fri, 12 Jul 2024 10:46:02 +0800 (CST) Date: Fri, 12 Jul 2024 10:46:02 +0800 From: Honggang LI To: Zhu Yanjun Cc: Greg Sword , zyjzyj2000@gmail.com, jgg@ziepe.ca, leon@kernel.org, rpearsonhpe@gmail.com, linux-rdma@vger.kernel.org Subject: Re: [PATCH] RDMA/rxe: Restore tasklet call for rxe_cq.c Message-ID: References: <20240711014006.11294-1-honggangli@163.com> Precedence: bulk X-Mailing-List: linux-rdma@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: X-CM-TRANSID:_____wDnDzfqmJBmKWHIAA--.747S2 X-Coremail-Antispam: 1Uf129KBjvdXoWruw43Zw45Zw4UWryrJw4xJFb_yoWDZrXEgF Z8GFyjkrW2vw4UKryUKFs3XFsYg3y5Gry8J3y5GFy3Cry5A34DZr48Wr93uw1rX395CFyU u34avayv9r1q9jkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7IUbVc_PUUUUU== X-CM-SenderInfo: 5krqwwxdqjzxi6rwjhhfrp/1tbiDxAaRWVOFLA+OAAAsJ On Thu, Jul 11, 2024 at 03:46:24PM +0200, Zhu Yanjun wrote: > Subject: Re: [PATCH] RDMA/rxe: Restore tasklet call for rxe_cq.c > > > > > Please explain the deadlock in details. > > I read the discussion carefully. I have the following: > 1). This problem is not from RXE. It seems to be related with krping > modules. As such, the root cause is not in RXE. It is not good to fix this > problem in RXE. Can't say it a problem in krping. As krping works over irdma/mlx5/siw. The deadlock only happens with rxe. > > 2). In the kernel upstream, tasklet is marked obsolete and has some design > flaws. So replacing workqueue with tasklet in RXE does not keep up with the > kernel upstream. > > https://patchwork.kernel.org/project/linux-rdma/cover/20240621050525.3720069-1-allen.lkml@gmail.com/ > In this link, there are some work to replace tasklet with BH workqueue. > As such, it is not good to replace workqueue with tasklet. Yes, you are right. Tasklet is obsoleted. We need a better solution for this issue. Please feel free to drop the patch.