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The ring buffer code of XDP sockets is missing a memory barrier on the consumer side between the load of the data and the write that signals that it is ok for the producer to put new data into the buffer. On architectures that does not guarantee that stores are not reordered with older loads, the producer might put data into the ring before the consumer had the chance to read it. As IA does guarantee this ordering, it would only need a compiler barrier here, but there are no primitives in Linux for this specific case (hinder writes to be ordered before older reads) so I had to add a smp_mb() here which will translate into a run-time synch operation on IA. Added a longish comment in the code explaining what each barrier in the ring implementation accomplishes and what would happen if we removed one of them. Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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| .. | ||
| Kconfig | ||
| Makefile | ||
| xdp_umem.c | ||
| xdp_umem.h | ||
| xsk_diag.c | ||
| xsk_queue.c | ||
| xsk_queue.h | ||
| xsk.c | ||
| xsk.h | ||