From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Date: Thu, 04 Feb 2016 11:23:08 -0500 Subject: [LTP] [PATCH] ftrace_stress_test: check if tracing_enabled is supported In-Reply-To: <20160204151100.GA15075@rei.suse.cz> References: <1450934523-69837-1-git-send-email-chuhu@redhat.com> <20160204142830.GA11527@rei.lan> <1454598367.1195.45.camel@fedora> <20160204151100.GA15075@rei.suse.cz> Message-ID: <1454602988.1195.56.camel@fedora> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ltp@lists.linux.it On Thu, 2016-02-04 at 16:11 +0100, Cyril Hrubis wrote: > Also looking at the stress test all it does is writing to various files > (in several background loops) that store tracing parameters. Is that > even reasonable test? I guess that it can find out race conditions > between functions that handle the write for the options... I don't use the LTP tests for ftrace, so I wouldn't know. > > And it uses the tracing_on file as well. So we can just skip starting > the loop writes to the ftrace_enabled file if it's not present. > ftrace_enabled is completely different. It disables function tracing capabilities (and should be avoided if /sys/kernel/debug/tracing/options/function-trace is present. As that will only disable function hooks for tracing, where /proc/sys/kernel/ftrace_enabled disables *all* hooks (including those for live kernel patching). Which I need to make a patch to prevent that :-/ -- Steve