* [PATCH] trace-cmd record: Verify that splice works before using it
@ 2022-06-08 17:05 Steven Rostedt
2023-01-19 21:03 ` Johannes Berg
0 siblings, 1 reply; 3+ messages in thread
From: Steven Rostedt @ 2022-06-08 17:05 UTC (permalink / raw)
To: Linux Trace Devel; +Cc: Johannes Berg
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Add a test to make sure that splice works on the source directory before
using it, and if not automatically switch over to read/write method.
Suggested-by: Johannes Berg <johannes@sipsolutions.net>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=213659
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
Johannes, can you test this?
I want to make sure that it fixes the issue.
lib/trace-cmd/trace-recorder.c | 38 ++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/lib/trace-cmd/trace-recorder.c b/lib/trace-cmd/trace-recorder.c
index c83337899098..c7ef13c851d2 100644
--- a/lib/trace-cmd/trace-recorder.c
+++ b/lib/trace-cmd/trace-recorder.c
@@ -220,6 +220,41 @@ tracecmd_create_buffer_recorder_fd2(int fd, int fd2,
int cpu, unsigned flags, return NULL;
}
+static void verify_splice(const char *file, unsigned *flags)
+{
+ int brass[2];
+ int ret;
+ int fd;
+
+ fd = open(file, O_WRONLY | O_CREAT | O_TRUNC | O_LARGEFILE, 0644);
+ if (fd < 0)
+ return; /* Will fail by the caller too */
+
+ if (pipe(brass) < 0)
+ goto fail_pipe;
+
+ ret = splice(brass[0], NULL, fd, NULL, 0, SPLICE_F_NONBLOCK);
+ if (ret < 0)
+ goto fail_splice;
+
+ out_pipe:
+ close(brass[0]);
+ close(brass[1]);
+ out:
+ close(fd);
+ return;
+
+ fail_pipe:
+ tracecmd_warning("Failed opening pipe, trying read/write");
+ *flags |= TRACECMD_RECORD_NOSPLICE;
+ goto out;
+
+ fail_splice:
+ tracecmd_warning("Failed splice to file, trying read/write");
+ *flags |= TRACECMD_RECORD_NOSPLICE;
+ goto out_pipe;
+}
+
struct tracecmd_recorder *
tracecmd_create_buffer_recorder_fd(int fd, int cpu, unsigned flags, const
char *buffer) {
@@ -233,6 +268,9 @@ __tracecmd_create_buffer_recorder(const char *file, int
cpu, unsigned flags, struct tracecmd_recorder *recorder;
int fd;
+ if (!(flags & TRACECMD_RECORD_NOSPLICE))
+ verify_splice(file, &flags);
+
fd = open(file, O_WRONLY | O_CREAT | O_TRUNC | O_LARGEFILE, 0644);
if (fd < 0)
return NULL;
--
2.35.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] trace-cmd record: Verify that splice works before using it
2022-06-08 17:05 [PATCH] trace-cmd record: Verify that splice works before using it Steven Rostedt
@ 2023-01-19 21:03 ` Johannes Berg
2023-01-19 21:53 ` Steven Rostedt
0 siblings, 1 reply; 3+ messages in thread
From: Johannes Berg @ 2023-01-19 21:03 UTC (permalink / raw)
To: Steven Rostedt, Linux Trace Devel
On Wed, 2022-06-08 at 13:05 -0400, Steven Rostedt wrote:
> From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
>
> Add a test to make sure that splice works on the source directory before
> using it, and if not automatically switch over to read/write method.
>
> Suggested-by: Johannes Berg <johannes@sipsolutions.net>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=213659
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
> Johannes, can you test this?
> I want to make sure that it fixes the issue.
>
Umm, yeah, long time ago. Sorry, I've been meaning to do that, but it
isn't easy, so I kept pushing it off.
My use case for this was UML with hostfs, which I've since fixed (kernel
upstream commit 1568cb0e6d97 ("hostfs: support splice_write"); I can
revert that easily of course, but then I still have to build my own
trace-cmd with that patch... But that needs libtracefs 1.6 which even
Fedora doesn't ship.
Given that you've merged the patch already, I think I'll just give up on
testing it, sorry about that.
johannes
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] trace-cmd record: Verify that splice works before using it
2023-01-19 21:03 ` Johannes Berg
@ 2023-01-19 21:53 ` Steven Rostedt
0 siblings, 0 replies; 3+ messages in thread
From: Steven Rostedt @ 2023-01-19 21:53 UTC (permalink / raw)
To: Johannes Berg; +Cc: Linux Trace Devel
On Thu, 19 Jan 2023 22:03:27 +0100
Johannes Berg <johannes@sipsolutions.net> wrote:
> On Wed, 2022-06-08 at 13:05 -0400, Steven Rostedt wrote:
> > From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
> >
> > Add a test to make sure that splice works on the source directory before
> > using it, and if not automatically switch over to read/write method.
> >
> > Suggested-by: Johannes Berg <johannes@sipsolutions.net>
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=213659
> > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> > ---
> > Johannes, can you test this?
> > I want to make sure that it fixes the issue.
> >
>
> Umm, yeah, long time ago. Sorry, I've been meaning to do that, but it
> isn't easy, so I kept pushing it off.
>
> My use case for this was UML with hostfs, which I've since fixed (kernel
> upstream commit 1568cb0e6d97 ("hostfs: support splice_write"); I can
> revert that easily of course, but then I still have to build my own
> trace-cmd with that patch... But that needs libtracefs 1.6 which even
> Fedora doesn't ship.
They should ;-)
>
> Given that you've merged the patch already, I think I'll just give up on
> testing it, sorry about that.
No worries. I'll just close the bug. Thanks, for responding.
-- Steve
^ permalink raw reply [flat|nested] 3+ messages in thread
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