lib: os: mpsc_pbuf: fix potential semaphore wait forever #98733
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zephyrbot added area: Tests | @nordic-krch |
 this case easy find in native_sim and qemu_x86 and other platform sometimes happen. |
One thread calls mpsc_pbuf_alloc to produce data, which invokes add_skip_item and steps into k_sem_take. Another thread calls mpsc_pbuf_claim to consume data. In this condition, mpsc_pbuf_claim has only small remaining space and needs to call rd_idx_inc to reserve space, but there is still no data available. The consumer should call k_sem_give to wake mpsc_pbuf_alloc again, so the producer can allocate space and continue producing data. Without this wake-up, the producer thread may wait forever in k_sem_take, leading to a deadlock situation. Signed-off-by: Fei Wang <fei.wang@jaguarmicro.com>
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| @kartben manual trigger Twister Status / all jobs . thanks |
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One thread calls mpsc_pbuf_alloc to produce data, which invokes add_skip_item and steps into k_sem_take.
Another thread calls mpsc_pbuf_claim to consume data. In this condition, mpsc_pbuf_claim has only small remaining space and needs to call rd_idx_inc to reserve space, but there is still no data available.
The consumer should call k_sem_give to wake mpsc_pbuf_alloc again, so the producer can allocate space and continue producing data.
Without this wake-up, the producer thread may wait forever in k_sem_take, leading to a deadlock situation.