From patchwork Tue Jul 30 05:15:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 13746560 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 83ABA16728B; Tue, 30 Jul 2024 05:14:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722316496; cv=none; b=arHwg+VQ7F6Ra2fy0ij2ALce9xRndBVt7cNjSLqRV31ek6grnOzyCXglX9IBYl+vw3r34SxjAgdqzZWHk+UDi65M5tgOSfztm3HsfNzofc8xw4uBFzuAyOICq3S/Z4H1sjcEHzTc/2CwOinsKiBCnluG1P0RBzAnXsRdwDA6OkU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722316496; c=relaxed/simple; bh=mF4FNYo87q0v9iKFXaWZ3IE5/zlazvPTfa1axnXq7RM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=X8ZulrBtjPByUDe58nVLmuYpzIXJgENn0l65yqKmUUoBodEj0DyiUEo47+DdYGd4ImwPj8aOPDiE8vlq/WJFA03yvgXSsPCXsIF6UIkJMexTr4D7QvNEpjEeL4Ii+fdC+vhIrynT0vN54CMEuoKJaUTYvHC0N+AjY2tWPfKq4mU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qUASOf7o; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qUASOf7o" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5D4F6C32782; Tue, 30 Jul 2024 05:14:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722316496; bh=mF4FNYo87q0v9iKFXaWZ3IE5/zlazvPTfa1axnXq7RM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qUASOf7oQWW8nwXMgsoXd79ICUXLNfLmQbMWE7QW6pr/N7IEukufOpkv6QhNuCYNF aGZCtXFPDxjABzsdWKds7bO7EqZQLPLE6bOWfBh2gPiBezbs9G8pAfDMomimtgSHY2 U3/MAnIMF3X7qUcA4sS52E8meWHxkd4efnv1pPHv3eWOkyFgv5STY7ZfoDwflKukmW hfLdqzeEFosKMZUY/3iC+yDcIv0axWgrmWo4TLp4+uzh/j9iSUnN/T1c9EoGxSCxg+ 1UdsmEk6Wx8lQRxvGEg0KT9rDK4qbtDf8uxQOjcFzfqhYWn7pCQWM5ZdQ5b1BBFDRM 3ROjlKSDwLTqw== From: viro@kernel.org To: linux-fsdevel@vger.kernel.org Cc: amir73il@gmail.com, bpf@vger.kernel.org, brauner@kernel.org, cgroups@vger.kernel.org, kvm@vger.kernel.org, netdev@vger.kernel.org, torvalds@linux-foundation.org Subject: [PATCH 10/39] get rid of perf_fget_light(), convert kernel/events/core.c to CLASS(fd) Date: Tue, 30 Jul 2024 01:15:56 -0400 Message-Id: <20240730051625.14349-10-viro@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240730051625.14349-1-viro@kernel.org> References: <20240730050927.GC5334@ZenIV> <20240730051625.14349-1-viro@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Al Viro Lift fdget() and fdput() out of perf_fget_light(), turning it into is_perf_file(struct fd f). The life gets easier in both callers if we do fdget() unconditionally, including the case when we are given -1 instead of a descriptor - that avoids a reassignment in perf_event_open(2) and it avoids a nasty temptation in _perf_ioctl() where we must *not* lift output_event out of scope for output. Signed-off-by: Al Viro Reviewed-by: Christian Brauner --- kernel/events/core.c | 49 +++++++++++++++----------------------------- 1 file changed, 16 insertions(+), 33 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index fd2ac9c7fd77..dae815c30514 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5895,18 +5895,9 @@ EXPORT_SYMBOL_GPL(perf_event_period); static const struct file_operations perf_fops; -static inline int perf_fget_light(int fd, struct fd *p) +static inline bool is_perf_file(struct fd f) { - struct fd f = fdget(fd); - if (!fd_file(f)) - return -EBADF; - - if (fd_file(f)->f_op != &perf_fops) { - fdput(f); - return -EBADF; - } - *p = f; - return 0; + return !fd_empty(f) && fd_file(f)->f_op == &perf_fops; } static int perf_event_set_output(struct perf_event *event, @@ -5954,20 +5945,14 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon case PERF_EVENT_IOC_SET_OUTPUT: { - int ret; + CLASS(fd, output)(arg); // arg == -1 => empty + struct perf_event *output_event = NULL; if (arg != -1) { - struct perf_event *output_event; - struct fd output; - ret = perf_fget_light(arg, &output); - if (ret) - return ret; + if (!is_perf_file(output)) + return -EBADF; output_event = fd_file(output)->private_data; - ret = perf_event_set_output(event, output_event); - fdput(output); - } else { - ret = perf_event_set_output(event, NULL); } - return ret; + return perf_event_set_output(event, output_event); } case PERF_EVENT_IOC_SET_FILTER: @@ -12474,7 +12459,6 @@ SYSCALL_DEFINE5(perf_event_open, struct perf_event_attr attr; struct perf_event_context *ctx; struct file *event_file = NULL; - struct fd group = EMPTY_FD; struct task_struct *task = NULL; struct pmu *pmu; int event_fd; @@ -12545,10 +12529,12 @@ SYSCALL_DEFINE5(perf_event_open, if (event_fd < 0) return event_fd; + CLASS(fd, group)(group_fd); // group_fd == -1 => empty if (group_fd != -1) { - err = perf_fget_light(group_fd, &group); - if (err) + if (!is_perf_file(group)) { + err = -EBADF; goto err_fd; + } group_leader = fd_file(group)->private_data; if (flags & PERF_FLAG_FD_OUTPUT) output_event = group_leader; @@ -12560,7 +12546,7 @@ SYSCALL_DEFINE5(perf_event_open, task = find_lively_task_by_vpid(pid); if (IS_ERR(task)) { err = PTR_ERR(task); - goto err_group_fd; + goto err_fd; } } @@ -12827,12 +12813,11 @@ SYSCALL_DEFINE5(perf_event_open, mutex_unlock(¤t->perf_event_mutex); /* - * Drop the reference on the group_event after placing the - * new event on the sibling_list. This ensures destruction - * of the group leader will find the pointer to itself in - * perf_group_detach(). + * File reference in group guarantees that group_leader has been + * kept alive until we place the new event on the sibling_list. + * This ensures destruction of the group leader will find + * the pointer to itself in perf_group_detach(). */ - fdput(group); fd_install(event_fd, event_file); return event_fd; @@ -12851,8 +12836,6 @@ SYSCALL_DEFINE5(perf_event_open, err_task: if (task) put_task_struct(task); -err_group_fd: - fdput(group); err_fd: put_unused_fd(event_fd); return err;