From patchwork Tue Jan 18 20:43:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beau Belgrave X-Patchwork-Id: 12716898 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A74BC43217 for ; Tue, 18 Jan 2022 20:43:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349387AbiARUnj (ORCPT ); Tue, 18 Jan 2022 15:43:39 -0500 Received: from linux.microsoft.com ([13.77.154.182]:43838 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349130AbiARUnd (ORCPT ); Tue, 18 Jan 2022 15:43:33 -0500 Received: from localhost.localdomain (c-73-140-2-214.hsd1.wa.comcast.net [73.140.2.214]) by linux.microsoft.com (Postfix) with ESMTPSA id F335220B9283; Tue, 18 Jan 2022 12:43:32 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com F335220B9283 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1642538613; bh=kv0wHco5EwAEJeOx8KcU5U1Oq+sRrfrasJlUzpwkVMg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GN0474JlUnGY3rhpKvqTfScmeQBuGYpooiTO7pzQ4FkVyIWHp7M66XEfF1qCOWtym WXbBA0expHMu8NJWbbZo+gQ9iMPbu6AoOeRErpqYfrruraB5Pfkm0u7LfmCU1XQVZ6 T4tShzSch+aHF7NHOnzeyH2PInYF3BQgl7oM60bM= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org Cc: linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org, beaub@linux.microsoft.com Subject: [PATCH v10 11/12] user_events: Add sample code for typical usage Date: Tue, 18 Jan 2022 12:43:25 -0800 Message-Id: <20220118204326.2169-12-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220118204326.2169-1-beaub@linux.microsoft.com> References: <20220118204326.2169-1-beaub@linux.microsoft.com> Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Add sample code for user_events typical usage to show how to register and monitor status, as well as to write out data. Signed-off-by: Beau Belgrave --- samples/user_events/Makefile | 5 ++ samples/user_events/example.c | 91 +++++++++++++++++++++++++++++++++++ 2 files changed, 96 insertions(+) create mode 100644 samples/user_events/Makefile create mode 100644 samples/user_events/example.c diff --git a/samples/user_events/Makefile b/samples/user_events/Makefile new file mode 100644 index 000000000000..7252b589db57 --- /dev/null +++ b/samples/user_events/Makefile @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0 +CFLAGS += -Wl,-no-as-needed -Wall -I../../usr/include + +example: example.o +example.o: example.c diff --git a/samples/user_events/example.c b/samples/user_events/example.c new file mode 100644 index 000000000000..4f5778e441c0 --- /dev/null +++ b/samples/user_events/example.c @@ -0,0 +1,91 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2021, Microsoft Corporation. + * + * Authors: + * Beau Belgrave + */ + +#include +#include +#include +#include +#include +#include +#include + +/* Assumes debugfs is mounted */ +const char *data_file = "/sys/kernel/debug/tracing/user_events_data"; +const char *status_file = "/sys/kernel/debug/tracing/user_events_status"; + +static int event_status(char **status) +{ + int fd = open(status_file, O_RDONLY); + + *status = mmap(NULL, sysconf(_SC_PAGESIZE), PROT_READ, + MAP_SHARED, fd, 0); + + close(fd); + + if (*status == MAP_FAILED) + return -1; + + return 0; +} + +static int event_reg(int fd, const char *command, int *status, int *write) +{ + struct user_reg reg = {0}; + + reg.size = sizeof(reg); + reg.name_args = (__u64)command; + + if (ioctl(fd, DIAG_IOCSREG, ®) == -1) + return -1; + + *status = reg.status_index; + *write = reg.write_index; + + return 0; +} + +int main(int argc, char **argv) +{ + int data_fd, status, write; + char *status_page; + struct iovec io[2]; + __u32 count = 0; + + if (event_status(&status_page) == -1) + return errno; + + data_fd = open(data_file, O_RDWR); + + if (event_reg(data_fd, "test u32 count", &status, &write) == -1) + return errno; + + /* Setup iovec */ + io[0].iov_base = &write; + io[0].iov_len = sizeof(write); + io[1].iov_base = &count; + io[1].iov_len = sizeof(count); + +ask: + printf("Press enter to check status...\n"); + getchar(); + + /* Check if anyone is listening */ + if (status_page[status]) { + /* Yep, trace out our data */ + writev(data_fd, (const struct iovec *)io, 2); + + /* Increase the count */ + count++; + + printf("Something was attached, wrote data\n"); + } + + goto ask; + + return 0; +}