https://github.com/torvalds/linux
Revision 3d2353de81061cab4b9d68b3e1dc69cbec1451ea authored by Steven Rostedt (VMware) on 13 May 2020, 19:18:01 UTC, committed by Steven Rostedt (VMware) on 14 May 2020, 12:50:51 UTC
If the function tracer is running and the trace file is read (which uses the
ring buffer iterator), the iterator can get in sync with the writes, and
caues it to fail to find a page with content it can read three times. This
causes a warning and deactivation of the ring buffer code.
Looking at the other cases of failure to get an event, it appears that
there's a chance that the writer could cause them too. Since the iterator is
a "best effort" to read the ring buffer if there's an active writer (the
consumer reader is made for this case "see trace_pipe"), if it fails to get
an event after three tries, simply give up and return NULL. Don't warn, nor
disable the ring buffer on this failure.
Link: https://lore.kernel.org/r/20200429090508.GG5770@shao2-debian
Reported-by: kernel test robot <lkp@intel.com>
Fixes: ff84c50cfb4b ("ring-buffer: Do not die if rb_iter_peek() fails more than thrice")
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
1 parent 59566b0
Tip revision: 3d2353de81061cab4b9d68b3e1dc69cbec1451ea authored by Steven Rostedt (VMware) on 13 May 2020, 19:18:01 UTC
ring-buffer: Don't deactivate the ring buffer on failed iterator reads
ring-buffer: Don't deactivate the ring buffer on failed iterator reads
Tip revision: 3d2353d
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| .clang-format | -rw-r--r-- | 15.8 KB |
| .cocciconfig | -rw-r--r-- | 59 bytes |
| .get_maintainer.ignore | -rw-r--r-- | 71 bytes |
| .gitattributes | -rw-r--r-- | 62 bytes |
| .gitignore | -rw-r--r-- | 1.7 KB |
| .mailmap | -rw-r--r-- | 15.1 KB |
| COPYING | -rw-r--r-- | 496 bytes |
| CREDITS | -rw-r--r-- | 97.4 KB |
| Kbuild | -rw-r--r-- | 1.3 KB |
| Kconfig | -rw-r--r-- | 595 bytes |
| MAINTAINERS | -rw-r--r-- | 539.4 KB |
| Makefile | -rw-r--r-- | 59.9 KB |
| README | -rw-r--r-- | 727 bytes |
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