This series addresses multiple issues discovered with the dynamic ring buffer resizing.
I have managed to reproduce a ring_buffer_read_page() race with $ while true; do for i in 8 16 32; do echo $i > /sys/kernel/tracing/buffer_subbuf_size_kb; sleep 0.1; done; done Changelog: v9: - Fix splice read loop when buffer size changes at the same time (Steven) - Allow splice for all static buffers (via memcpy) - Rebase on 7.3-rc1 v8 (https://lore.kernel.org/all/[email protected]/): - ring_buffer_read_page() handles gracefully read_page/reader_page order mismatch (Steven) v7 (https://lore.kernel.org/linux-trace-kernel/[email protected]/): - Match the "static" rb limit with bpage::id bitwidth - Cover another 32-bit truncation in rb_range_buffer (Sashiko) - Fix uninitialized spare_size (Sashiko) v6 (https://lore.kernel.org/all/[email protected]/): - New prototype for ring_buffer_alloc_read_page() (Steven) - ring_buffer_read_page() to return -EAGAIN (Steven) - Keep nr_pages "unsigned long" (Steven) - Repase on ring-buffer/next (Drop most of the patches) v5 (https://lore.kernel.org/all/[email protected]/): - Reset info->spare_read only when data is in the ring-buffer (Sashiko) - Use `unsigned long` for subbuf_size declaration to avoid 32-bit truncation. (Sashiko) - Make cpu_buffer::free_page a buffer_read_data_page - Update kerneldoc for ring_buffer_alloc_read_page() v4 (https://lore.kernel.org/all/[email protected]/): - Add rb_subbuf_start() helper (Steven) - kerneldoc additions - Fix races in trace_pipe_raw readers - Use rb_subbuf_capacity() in ring_buffer_subbuf_order_set() - use rb_page_capacity() in ring_buffer_map_get_reader (Sashiko) - Fix 32-bit overflow in ring_buffer_subbuf_order_set() (Sashiko) - Hold cpu_buffer::lock when modifying cpu_buffer->free_page in ring_buffer_subbuf_order_set (Sashiko) v3 (https://lore.kernel.org/all/[email protected]/): - Drop first 3 patches (Rebased on 7.2-rc7) - Add a patch to align "nr_pages" to unsigned int - Add a patch to remove useless trace_buffer::cpus - Add unsigned long cast for rb_subbuf_size() - subbuf_order fix for rb_free_cpu_buffer() (Sashiko) - Use __always_inline just like the other accessors for the hot-path. v2 (https://lore.kernel.org/all/[email protected]/): - Prevent resizing of the persistent ring buffer - Add missing bpage::order init - Rework subbuf_size/subbuf_order (Sashiko) - Remove ring_buffer_per_cpu::mapped - Dynamically calculate trace_buffer::max_data_size v1 (https://lore.kernel.org/all/[email protected]/) Vincent Donnefort (4): ring-buffer: Allow splice reads on static buffers tracing: Fix subbuf resize races with trace_pipe_raw readers ring-buffer: Cap static ring buffer nr_pages ring-buffer: Prevent truncation of nr_pages / nr_subbufs include/linux/ring_buffer.h | 5 +- kernel/trace/ring_buffer.c | 224 +++++++++++++++++---------- kernel/trace/ring_buffer_benchmark.c | 6 +- kernel/trace/trace.c | 95 +++++------- kernel/trace/trace.h | 9 +- 5 files changed, 196 insertions(+), 143 deletions(-) base-commit: cee9395acd8043be0644b25c34bfa86623f2b935 -- 2.55.0.897.gb25b4bd76c-goog
