On 2023/9/20 1:01, Suzuki K Poulose wrote: > On 19/09/2023 14:03, Yicong Yang wrote: >> On 2023/9/15 20:53, Suzuki K Poulose wrote: >>> On 14/09/2023 12:22, Yicong Yang wrote: >>>> From: Junhao He <hejunhao3@xxxxxxxxxx> >>>> >>>> When start trace with perf option "-C $cpu" and immediately stop it >>>> with SIGTERM or others, the perf core will invoke pmu::read() while >>>> the driver doesn't implement it. Add a dummy pmu::read() to avoid >>>> any issues. >>> >>> What issues are we talking about here ? Shouldn't the core perf >>> skip the call, if pmu::read() is not available ? >>> >> >> Actually no, the core doesn't check it. So I think that's why some PMUs >> like SPE implements a dummy pmu::read() callback. Otherwise we'll >> dereference a NULL pointer. >> >> Currently we only met this on emulated platforms with very slow CPUs, >> follow the instructions in the commit above. > > Ok, then it calls for a Fixes tag. Please tag it to the commit that > introduced the PMU. > Sure. I'll add the tag in v3. Thanks.
