From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.18]) (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 B1BFC17C9E8; Wed, 3 Jul 2024 14:07:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720015638; cv=none; b=cZhuq6Q2+mCL1TxBpKuXUfFiynzO9joFk8Alq8oziBox7SwUkGN+LgCrDLuzJfJ5Q8MFVq1RcNSMyrmHGb8jLGioIuPm3eLx/e7/m4kt/UCmsGZ2xzuzlNfoeaQ1Nw5PsP6ASPLfgQQeb3QKBMGUwIgJy2EZXkOAtS4vgZR+cZQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720015638; c=relaxed/simple; bh=MWZtVxjh3PFjIWGDTRmBv/J1DQS8L9dlFBlCzhsyd10=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=j6Reh7WbqCQLRnwOa8DvJFJigMVd5ylNB2HTOGY1PzOVbktXdXObO3HIIm2MWf/Mmtvh5HKeeQDNvDlcSVfFAgCC9AtWPpJ+v9rXF0XI9IA0tbHsteGVFB7/r/QGSegJp3zJqkx72TMkJrMBtm9qexsrNM5rJXE1Mp55axrsRCo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Vv2DXr1I; arc=none smtp.client-ip=192.198.163.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Vv2DXr1I" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1720015637; x=1751551637; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=MWZtVxjh3PFjIWGDTRmBv/J1DQS8L9dlFBlCzhsyd10=; b=Vv2DXr1I3VJY/hBYq3zAzjHcMy1Q1p4/9orh4trqI88lxQtJ5wYFAu/v c8sZQGtjsdtroglT8KRCSJ/A/xHHIthC45fwdnWBjGK+FG2VsP385ERj7 4ey7eQ1herNrNh5Q6ZX5rHB7diQeSI/xcKZur5oaePTGjy0SImgpsunaP VOmDmFzXxETOjrSSMReY/ZDNAN2CU/rOO4V2Bam12MnphpcLFuF9qIt76 tUDATNEptuAs2/2bHcuRxek/3VZI2izMRp5i8I9Y4o9WuPhi0Uq7k50Uw /A6xTUPS1yYDPNB/qKcb6AHjOipH2KvRahDUWzyValU7LtP+POV8xMtop A==; X-CSE-ConnectionGUID: vZ76/Iq6RqKhm9hbhc6ibQ== X-CSE-MsgGUID: +/P0uKcsQeKgH7CZzzu6hA== X-IronPort-AV: E=McAfee;i="6700,10204,11121"; a="16900702" X-IronPort-AV: E=Sophos;i="6.09,182,1716274800"; d="scan'208";a="16900702" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jul 2024 07:07:17 -0700 X-CSE-ConnectionGUID: CfWTawYGR9WQ+E4bqntFRQ== X-CSE-MsgGUID: 4H/zJIhMSgOQsEe6WsNVOg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,182,1716274800"; d="scan'208";a="46693470" Received: from linux-pnp-server-16.sh.intel.com ([10.239.177.152]) by orviesa006.jf.intel.com with ESMTP; 03 Jul 2024 07:07:13 -0700 From: Yu Ma To: viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, mjguzik@gmail.com, edumazet@google.com Cc: yu.ma@intel.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, pan.deng@intel.com, tianyou.li@intel.com, tim.c.chen@intel.com, tim.c.chen@linux.intel.com Subject: [PATCH v3 1/3] fs/file.c: remove sanity_check and add likely/unlikely in alloc_fd() Date: Wed, 3 Jul 2024 10:33:09 -0400 Message-ID: <20240703143311.2184454-2-yu.ma@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240703143311.2184454-1-yu.ma@intel.com> References: <20240614163416.728752-1-yu.ma@intel.com> <20240703143311.2184454-1-yu.ma@intel.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit alloc_fd() has a sanity check inside to make sure the struct file mapping to the allocated fd is NULL. Remove this sanity check since it can be assured by exisitng zero initilization and NULL set when recycling fd. Meanwhile, add likely/unlikely and expand_file() call avoidance to reduce the work under file_lock. Reviewed-by: Tim Chen Signed-off-by: Yu Ma --- fs/file.c | 38 ++++++++++++++++---------------------- 1 file changed, 16 insertions(+), 22 deletions(-) diff --git a/fs/file.c b/fs/file.c index a3b72aa64f11..5178b246e54b 100644 --- a/fs/file.c +++ b/fs/file.c @@ -515,28 +515,29 @@ static int alloc_fd(unsigned start, unsigned end, unsigned flags) if (fd < files->next_fd) fd = files->next_fd; - if (fd < fdt->max_fds) + if (likely(fd < fdt->max_fds)) fd = find_next_fd(fdt, fd); + error = -EMFILE; + if (unlikely(fd >= fdt->max_fds)) { + error = expand_files(files, fd); + if (error < 0) + goto out; + /* + * If we needed to expand the fs array we + * might have blocked - try again. + */ + if (error) + goto repeat; + } + /* * N.B. For clone tasks sharing a files structure, this test * will limit the total number of files that can be opened. */ - error = -EMFILE; - if (fd >= end) - goto out; - - error = expand_files(files, fd); - if (error < 0) + if (unlikely(fd >= end)) goto out; - /* - * If we needed to expand the fs array we - * might have blocked - try again. - */ - if (error) - goto repeat; - if (start <= files->next_fd) files->next_fd = fd + 1; @@ -546,13 +547,6 @@ static int alloc_fd(unsigned start, unsigned end, unsigned flags) else __clear_close_on_exec(fd, fdt); error = fd; -#if 1 - /* Sanity check */ - if (rcu_access_pointer(fdt->fd[fd]) != NULL) { - printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd); - rcu_assign_pointer(fdt->fd[fd], NULL); - } -#endif out: spin_unlock(&files->file_lock); @@ -618,7 +612,7 @@ void fd_install(unsigned int fd, struct file *file) rcu_read_unlock_sched(); spin_lock(&files->file_lock); fdt = files_fdtable(files); - BUG_ON(fdt->fd[fd] != NULL); + WARN_ON(fdt->fd[fd] != NULL); rcu_assign_pointer(fdt->fd[fd], file); spin_unlock(&files->file_lock); return; -- 2.43.0