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charset="UTF-8" Content-Transfer-Encoding: quoted-printable Bart=C5=82omiej reported a remote tracing issue on Android kernel branches. Although that code differs from mainline, investigating the report showed that upstream has the same underlying shortfalls: 1. Potential corruption of a simple ring buffer because it does not prevent swapping the reader page with the head when the reader page is already the tail page (nor order the page::commit reset before updating tail_page). 2. Potential failure of rb_advance_reader() because __rb_get_reader_page_from_remote() checks rb_num_of_entries() before checking the reader page commit via rb_page_size(), and lacks memory barriers ordering page::commit and meta::entries. While at it, order page::commit with page::data and page::time_stamp (patch 3) and add the missing pages_read increment on remote reader page swaps (patch 4). Vincent Donnefort (4): ring-buffer: Skip remote reader page swap when on tail ring-buffer: Check remote reader page commit before meta entries ring-buffer: Order remote page commit with data and timestamp ring-buffer: Increment pages_read on remote ring buffer page swap kernel/trace/ring_buffer.c | 46 +++++++++++++++++++++---------- kernel/trace/simple_ring_buffer.c | 26 ++++++++++++++++- 2 files changed, 57 insertions(+), 15 deletions(-) base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4 --=20 2.56.0.611.g1030f0b940-goog