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a64af0ef1c
Given libbpf is a generic library and not restricted to x86-64 only, the compiler barrier in bpf_perf_event_read_simple() after fetching the head needs to be replaced with smp_rmb() at minimum. Also, writing out the tail we should use WRITE_ONCE() to avoid store tearing. Now that we have the logic in place in ring_buffer_read_head() and ring_buffer_write_tail() helper also used by perf tool which would select the correct and best variant for a given architecture (e.g. x86-64 can avoid CPU barriers entirely), make use of these in order to fix bpf_perf_event_read_simple(). Fixes:d0cabbb021("tools: bpf: move the event reading loop to libbpf") Fixes:39111695b1("samples: bpf: add bpf_perf_event_output example") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.