Public bug reported: sphde fails to build on arm64 and armhf in stonking (and resolute). The build is killed after 150 minutes of inactivity in sphsinglepcqueue_ttt: https://launchpad.net/ubuntu/+source/sphde/1.4.0-5.1build2/+build/32794042
Debian has the same failure: https://bugs.debian.org/1125773 The test does not just hang; it deadlocks. Running it under gdb on an arm64 buildd showed that SPHSinglePCQueueAllocStrideEntry() fails in the producer thread, which then exits. The consumer thread spins forever waiting for entries that never arrive, and main() is blocked in pthread_join(). Root cause: arm and aarch64 use src/sasatom_generic.h, where sas_read_barrier(), sas_write_barrier() and sas_full_barrier() are compiler-only barriers (asm("" ::: "memory")). On a weakly ordered CPU, the producer can see the qtail advanced by SPHSinglePCQueueFreeNextEntry() while still reading the stale "allocated" entry header. As a result, SPHSinglePCQueueFull() says "not full" but the allocation fails. x86_64 and powerpc use real fences. Upstream master already uses __sync_synchronize() in the newer riscv and loongarch headers, but arm was never covered. Fix: make the generic barriers real fences (__atomic_thread_fence(__ATOMIC_SEQ_CST)), and add the missing load ordering in the single PC queue alloc/get functions. Test build with the patch: the full test suite passes (20/20) on arm64 and armhf: https://launchpad.net/~ubuntu-desktop/+archive/ubuntu/transitions/+build/33825522 https://launchpad.net/~ubuntu-desktop/+archive/ubuntu/transitions/+build/33825523 ** Affects: sphde (Ubuntu) Importance: Undecided Assignee: Sebastien Bacher (seb128) Status: Fix Committed ** Affects: sphde (Debian) Importance: Unknown Status: Unknown ** Tags: arm64 armhf ftbfs patch -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2170172 Title: sphde FTBFS on arm64/armhf: sphsinglepcqueue_ttt deadlocks due to missing memory barriers To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/sphde/+bug/2170172/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
