From patchwork Wed Oct 16 10:49:33 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu \(Google\)" X-Patchwork-Id: 836006 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 3A271207213; Wed, 16 Oct 2024 10:49:36 +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=1729075777; cv=none; b=pFvt0Meu7Stleybs4LB8IUhWHjkJaQCuVoMyNK+ffd1ZUE/VqFbr8rPXu2uAcOOYXsNX4EoaPPPIQYd3PtdOpBjLsqyHWKBVDvkb7Xu+5gBa4LzbcnoD86esi+Fd2Te2NIaAaYqDIQ/Hx3bEizvFN2syUHTD/ECFohFY6zuMgJo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729075777; c=relaxed/simple; bh=dXXEJ1CQa20I+ilEYAbWxf0KdobQfCvDGGlCEBYzd7Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=BjXmJGn8us4hLQQMwHAAUFYLZFdiZS9NWGIMCc4YI2fb+mZJnSCs8lcfGFrrR3yCo78qcHF0U7xs2bBZD2ievNy4Foqlz2XVy57JckzHPO+u6LrOBWOGo1PYwFLwdBrX3mgBaQ68Gf79KvMZGRxPv9NsXDpdo3lIfkHJvAbDhRc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WXciUSkg; 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="WXciUSkg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4E84C4CED0; Wed, 16 Oct 2024 10:49:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729075776; bh=dXXEJ1CQa20I+ilEYAbWxf0KdobQfCvDGGlCEBYzd7Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WXciUSkgnoSwjoP6bqZnBXB80ITHp8p507gbapxbzGdzjMom9IAp8JAPUPldrqzLF Mvbp3/C0zjtKx4fxLkAh5NBRdTkIAQ0xhnLY+XSsaQ5dAUSNdx55Pw3n+SlFA2Drg+ y1FCZbzWXBoKqoEmE0gqjthz8TvAPY+JNdRhjwTk4NZ/p69eJr2n9khtvPK6KPCGFw P6/LRJartBtlCn5IxJwGd5prJM9F1wcjvc1zrQlrDeSIllNvEQAaFUSR/gLBtJh+Ud HRTClN5bc8wyREr94Uukpo7m8a9eUjME4Mt/N2efXwIkR1sf+jf/2QhIfT3jG8JX25 ID7wFQMuzyo/Q== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Shuah Khan Cc: Masami Hiramatsu , Tom Zanussi , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v6 2/3] tracing/hist: Support POLLPRI event for poll on histogram Date: Wed, 16 Oct 2024 19:49:33 +0900 Message-ID: <172907577331.470540.11394819971376123947.stgit@mhiramat.roam.corp.google.com> X-Mailer: git-send-email 2.47.0.rc1.288.g06298d1525-goog In-Reply-To: <172907575534.470540.12941248697563459082.stgit@mhiramat.roam.corp.google.com> References: <172907575534.470540.12941248697563459082.stgit@mhiramat.roam.corp.google.com> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Masami Hiramatsu (Google) Since POLLIN will not be flashed until read the hist file, user needs to repeat read() and poll() on hist for monitoring the event continuously. But the read() is somewhat redundant only for monitoring events. This add POLLPRI poll event on hist, this event returns when a histogram is updated after open(), poll() or read(). Thus it is possible to wait next event without read(). Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Tom Zanussi --- kernel/trace/trace_events_hist.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 107eaa0f40f1..8819a8cc4d53 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -5598,6 +5598,7 @@ static void hist_trigger_show(struct seq_file *m, struct hist_file_data { struct file *file; u64 last_read; + u64 last_act; }; static u64 get_hist_hit_count(struct trace_event_file *event_file) @@ -5635,6 +5636,11 @@ static int hist_show(struct seq_file *m, void *v) hist_trigger_show(m, data, n++); } hist_file->last_read = get_hist_hit_count(event_file); + /* + * Update last_act too so that poll()/POLLPRI can wait for the next + * event after any syscall on hist file. + */ + hist_file->last_act = hist_file->last_read; out_unlock: mutex_unlock(&event_mutex); @@ -5648,6 +5654,7 @@ static __poll_t event_hist_poll(struct file *file, struct poll_table_struct *wai struct seq_file *m = file->private_data; struct hist_file_data *hist_file = m->private; __poll_t ret = 0; + u64 cnt; mutex_lock(&event_mutex); @@ -5659,8 +5666,13 @@ static __poll_t event_hist_poll(struct file *file, struct poll_table_struct *wai hist_poll_wait(file, wait); - if (hist_file->last_read != get_hist_hit_count(event_file)) - ret = EPOLLIN | EPOLLRDNORM; + cnt = get_hist_hit_count(event_file); + if (hist_file->last_read != cnt) + ret |= EPOLLIN | EPOLLRDNORM; + if (hist_file->last_act != cnt) { + hist_file->last_act = cnt; + ret |= EPOLLPRI; + } out_unlock: mutex_unlock(&event_mutex); @@ -5679,6 +5691,7 @@ static int event_hist_release(struct inode *inode, struct file *file) static int event_hist_open(struct inode *inode, struct file *file) { + struct trace_event_file *event_file; struct hist_file_data *hist_file; int ret; @@ -5689,13 +5702,25 @@ static int event_hist_open(struct inode *inode, struct file *file) hist_file = kzalloc(sizeof(*hist_file), GFP_KERNEL); if (!hist_file) return -ENOMEM; + + mutex_lock(&event_mutex); + event_file = event_file_data(file); + if (!event_file) { + ret = -ENODEV; + goto out_unlock; + } + hist_file->file = file; + hist_file->last_act = get_hist_hit_count(event_file); /* Clear private_data to avoid warning in single_open() */ file->private_data = NULL; ret = single_open(file, hist_show, hist_file); + +out_unlock: if (ret) kfree(hist_file); + mutex_unlock(&event_mutex); return ret; }