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Al Viro has been looking at the tracefs code, and has pointed out

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some issues. This contains one fix by me and one by Al. I'm sure that
 he'll come up with more but for now I tested these patches and they
 don't appear to have any negative impact on tracing.
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Merge tag 'trace-v4.8-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracefs fixes from Steven Rostedt:
 "Al Viro has been looking at the tracefs code, and has pointed out some
  issues.  This contains one fix by me and one by Al.  I'm sure that
  he'll come up with more but for now I tested these patches and they
  don't appear to have any negative impact on tracing"

* tag 'trace-v4.8-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  fix memory leaks in tracing_buffers_splice_read()
  tracing: Move mutex to protect against resetting of seq data
This commit is contained in:
Linus Torvalds 2016-09-25 18:40:13 -07:00
commit 4c04b4b534
1 changed files with 16 additions and 13 deletions
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29
kernel/trace/trace.c
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@ -5124,19 +5124,20 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
struct trace_iterator *iter = filp->private_data;
ssize_t sret;
/* return any leftover data */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (sret != -EBUSY)
return sret;
trace_seq_init(&iter->seq);
/*
* Avoid more than one consumer on a single file descriptor
* This is just a matter of traces coherency, the ring buffer itself
* is protected.
*/
mutex_lock(&iter->mutex);
/* return any leftover data */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (sret != -EBUSY)
goto out;
trace_seq_init(&iter->seq);
if (iter->trace->read) {
sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
if (sret)
@ -6163,9 +6164,6 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
return -EBUSY;
#endif
if (splice_grow_spd(pipe, &spd))
return -ENOMEM;
if (*ppos & (PAGE_SIZE - 1))
return -EINVAL;
@ -6175,6 +6173,9 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
len &= PAGE_MASK;
}
if (splice_grow_spd(pipe, &spd))
return -ENOMEM;
again:
trace_access_lock(iter->cpu_file);
entries = ring_buffer_entries_cpu(iter->trace_buffer->buffer, iter->cpu_file);
@ -6232,19 +6233,21 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
/* did we read anything? */
if (!spd.nr_pages) {
if (ret)
return ret;
goto out;
ret = -EAGAIN;
if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK))
return -EAGAIN;
goto out;
ret = wait_on_pipe(iter, true);
if (ret)
return ret;
goto out;
goto again;
}
ret = splice_to_pipe(pipe, &spd);
out:
splice_shrink_spd(&spd);
return ret;