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Revision 21f1b8a6636c4dbde4aa1ec0343f42eaf653ffcc authored by Paolo Abeni on 26 April 2019, 10:50:44 UTC, committed by David S. Miller on 28 April 2019, 02:07:24 UTC 
udp: fix GRO reception in case of length mismatch
 
Currently, the UDP GRO code path does bad things on some edge
conditions - Aggregation can happen even on packet with different
lengths.

Fix the above by rewriting the 'complete' condition for GRO
packets. While at it, note explicitly that we allow merging the
first packet per burst below gso_size.

Reported-by: Sean Tong <seantong114@gmail.com>
Fixes: e20cf8d3f1f7 ("udp: implement GRO for plain UDP sockets.")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Raw File
events-nmi.rst 
================
NMI Trace Events
================

These events normally show up here:

	/sys/kernel/debug/tracing/events/nmi


nmi_handler
-----------

You might want to use this tracepoint if you suspect that your
NMI handlers are hogging large amounts of CPU time.  The kernel
will warn if it sees long-running handlers::

	INFO: NMI handler took too long to run: 9.207 msecs

and this tracepoint will allow you to drill down and get some
more details.

Let's say you suspect that perf_event_nmi_handler() is causing
you some problems and you only want to trace that handler
specifically.  You need to find its address::

	$ grep perf_event_nmi_handler /proc/kallsyms
	ffffffff81625600 t perf_event_nmi_handler

Let's also say you are only interested in when that function is
really hogging a lot of CPU time, like a millisecond at a time.
Note that the kernel's output is in milliseconds, but the input
to the filter is in nanoseconds!  You can filter on 'delta_ns'::

	cd /sys/kernel/debug/tracing/events/nmi/nmi_handler
	echo 'handler==0xffffffff81625600 && delta_ns>1000000' > filter
	echo 1 > enable

Your output would then look like::

	$ cat /sys/kernel/debug/tracing/trace_pipe
	<idle>-0     [000] d.h3   505.397558: nmi_handler: perf_event_nmi_handler() delta_ns: 3236765 handled: 1
	<idle>-0     [000] d.h3   505.805893: nmi_handler: perf_event_nmi_handler() delta_ns: 3174234 handled: 1
	<idle>-0     [000] d.h3   506.158206: nmi_handler: perf_event_nmi_handler() delta_ns: 3084642 handled: 1
	<idle>-0     [000] d.h3   506.334346: nmi_handler: perf_event_nmi_handler() delta_ns: 3080351 handled: 1
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