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Peter Anvin" , Thomas Gleixner , Jingjie Jiang , Mukesh Rathor , Konrad Rzeszutek Wilk , stable@vger.kernel.org References: <20180509144605.5a220327@gandalf.local.home> From: Juergen Gross Message-ID: <54c0a807-87e3-866f-aaa8-de383d567d50@suse.com> Date: Fri, 11 May 2018 06:14:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180509144605.5a220327@gandalf.local.home> Content-Type: text/plain; charset=utf-8 Content-Language: de-DE Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 09/05/18 20:46, Steven Rostedt wrote: > > From: "Steven Rostedt (VMware)" > > Doing an audit of trace events, I discovered two trace events in the xen > subsystem that use a hack to create zero data size trace events. This is not > what trace events are for. Trace events add memory footprint overhead, and > if all you need to do is see if a function is hit or not, simply make that > function noinline and use function tracer filtering. > > Worse yet, the hack used was: > > __array(char, x, 0) > > Which creates a static string of zero in length. There's assumptions about > such constructs in ftrace that this is a dynamic string that is nul > terminated. This is not the case with these tracepoints and can cause > problems in various parts of ftrace. > > Nuke the trace events! > > Cc: stable@vger.kernel.org > Fixes: 95a7d76897c1e ("xen/mmu: Use Xen specific TLB flush instead of the generic one.") > Signed-off-by: Steven Rostedt (VMware) Any reason not sending this patch to the Xen maintainers? I can take it through the Xen tree. :-) Reviewed-by: Juergen Gross Juergen