On Thu, 8 Feb 2024 21:18:14 +0800 Huang Yiwei <quic_hyiwei@xxxxxxxxxxx> wrote: > Currently ftrace only dumps the global trace buffer on an OOPs. For > debugging a production usecase, instance trace will be helpful to > check specific problems since global trace buffer may be used for > other purposes. > > This patch extend the ftrace_dump_on_oops parameter to dump a specific > or multiple trace instances: > > - ftrace_dump_on_oops=0: as before -- don't dump > - ftrace_dump_on_oops[=1]: as before -- dump the global trace buffer > on all CPUs > - ftrace_dump_on_oops=2 or =orig_cpu: as before -- dump the global > trace buffer on CPU that triggered the oops > - ftrace_dump_on_oops=<instance_name>: new behavior -- dump the > tracing instance matching <instance_name> > - ftrace_dump_on_oops[=2/orig_cpu],<instance1_name>[=2/orig_cpu], > <instrance2_name>[=2/orig_cpu]: new behavior -- dump the global trace > buffer and multiple instance buffer on all CPUs, or only dump on CPU > that triggered the oops if =2 or =orig_cpu is given So we need to add that the syntax is: ftrace_dump_on_oops[=[<0|1|2|orig_cpu>,][<instance_name>[=<1|2|orig_cpu>][,...]] > > Also, the sysctl node can handle the input accordingly. > > Cc: Ross Zwisler <zwisler@xxxxxxxxxx> > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > Signed-off-by: Huang Yiwei <quic_hyiwei@xxxxxxxxxxx> > --- > .../admin-guide/kernel-parameters.txt | 26 ++- > Documentation/admin-guide/sysctl/kernel.rst | 30 +++- > include/linux/ftrace.h | 4 +- > include/linux/kernel.h | 1 + > kernel/sysctl.c | 4 +- > kernel/trace/trace.c | 156 +++++++++++++----- > kernel/trace/trace_selftest.c | 2 +- > 7 files changed, 168 insertions(+), 55 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 31b3a25680d0..3d6ea8e80c2f 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -1561,12 +1561,28 @@ > The above will cause the "foo" tracing instance to trigger > a snapshot at the end of boot up. > > - ftrace_dump_on_oops[=orig_cpu] > + ftrace_dump_on_oops[=2(orig_cpu) | =<instance>][,<instance> | > + ,<instance>=2(orig_cpu)] > [FTRACE] will dump the trace buffers on oops. > - If no parameter is passed, ftrace will dump > - buffers of all CPUs, but if you pass orig_cpu, it will > - dump only the buffer of the CPU that triggered the > - oops. > + If no parameter is passed, ftrace will dump global > + buffers of all CPUs, if you pass 2 or orig_cpu, it > + will dump only the buffer of the CPU that triggered > + the oops, or the specific instance will be dumped if > + its name is passed. Multiple instance dump is also > + supported, and instances are separated by commas. Each > + instance supports only dump on CPU that triggered the > + oops by passing 2 or orig_cpu to it. > + > + ftrace_dump_on_oops=foo=orig_cpu > + > + The above will dump only the buffer of "foo" instance > + on CPU that triggered the oops. > + > + ftrace_dump_on_oops,foo,bar=orig_cpu I believe the above is incorrect. It should be: ftrace_dump_on_oops=foo,bar=orig_cpu And you can add here as well: ftrace_dump_on_oops[=[<0|1|2|orig_cpu>,][<instance_name>[=<1|2|orig_cpu>][,...]] Thanks, --Steve > + > + The above will dump global buffer on all CPUs, the > + buffer of "foo" instance on all CPUs and the buffer > + of "bar" instance on CPU that triggered the oops. > > ftrace_filter=[function-list]
