Re: [PATCH v3 net-next] bpf: fix bpf_perf_event_read() helper
From: Peter Zijlstra <peterz@infradead.org>
Date: 2015-10-26 12:32:13
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On Sun, Oct 25, 2015 at 09:23:36AM -0700, Alexei Starovoitov wrote:
bpf_perf_event_read() muxes of -EINVAL into return value, but it's non ambiguous to the program whether it got an error or real counter value.
How can that be, the (u64)-EINVAL value is a valid counter value.. unlikely maybe, but still quite possible.