aspeed_smc: Calculate checksum on normal DMA #15
Conversation
This patch adds the missing checksum calculation on normal DMA transfer. According to the datasheet this is how the SMC should behave. Verified on AST1250 that the hardware matches the behaviour. Signed-off-by: Christian Svensson <bluecmd@google.com>
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Hi @bluecmd - have you sent this upstream? Ideally all of our patches would be at least on the upstream list(s), similar to how we handle kernel development. If you Cc the OpenBMC mailing list we can pick it up from there, as well as follow the conversation. Please also Cc @legoater and myself directly. |
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I have no idea how to submit kernel patches like these. If you have any documentation or guide I can follow then I can do that :-) |
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There's a description here of how to send qemu patches: https://github.com/qemu/qemu/blob/master/README#L52 |
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Thanks, this is correct indeed. I recently did some changes in my patchset 034ee5d#diff-1c5ed2b17fd2d1367fc3dd9db76216eeR722 I prefer to work with email patches, as this is how most open-source |
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@legoater I fully understand, no hard feelings. My goal was to raise awareness of this patch and have it merged to mainline one way or another - worst case I figured people would just redirect me to where to post it. Mission accomplished :-).
I don't fully understand what you mean here. I did look at that function, that's how I figured what was missing from the _rw one. The patch you're referring to is on the same branch as this fix. Btw, if your statement from your original post ("I will fix it directly in |
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please send you patch by email on the openbmc mailing list. I will comment there. |
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Patch sent |
Let start from the beginning: Commit b9e413d (in 2.9) "block: explicitly acquire aiocontext in aio callbacks that need it" added pairs of aio_context_acquire/release to mirror_write_complete and mirror_read_complete, when they were aio callbacks for blk_aio_* calls. Then, commit 2e1990b (in 3.0) "block/mirror: Convert to coroutines" dropped these blk_aio_* calls, than mirror_write_complete and mirror_read_complete are not callbacks more, and don't need additional aiocontext acquiring. Furthermore, mirror_read_complete calls blk_co_pwritev inside these pair of aio_context_acquire/release, which leads to the following dead-lock with mirror: (gdb) info thr Id Target Id Frame 3 Thread (LWP 145412) "qemu-system-x86" syscall () 2 Thread (LWP 145416) "qemu-system-x86" __lll_lock_wait () * 1 Thread (LWP 145411) "qemu-system-x86" __lll_lock_wait () (gdb) bt #0 __lll_lock_wait () #1 _L_lock_812 () #2 __GI___pthread_mutex_lock #3 qemu_mutex_lock_impl (mutex=0x561032dce420 <qemu_global_mutex>, file=0x5610327d8654 "util/main-loop.c", line=236) at util/qemu-thread-posix.c:66 #4 qemu_mutex_lock_iothread_impl #5 os_host_main_loop_wait (timeout=480116000) at util/main-loop.c:236 #6 main_loop_wait (nonblocking=0) at util/main-loop.c:497 #7 main_loop () at vl.c:1892 #8 main Printing contents of qemu_global_mutex, I see that "__owner = 145416", so, thr1 is main loop, and now it wants BQL, which is owned by thr2. (gdb) thr 2 (gdb) bt #0 __lll_lock_wait () #1 _L_lock_870 () #2 __GI___pthread_mutex_lock #3 qemu_mutex_lock_impl (mutex=0x561034d25dc0, ... #4 aio_context_acquire (ctx=0x561034d25d60) #5 dma_blk_cb #6 dma_blk_io #7 dma_blk_read #8 ide_dma_cb #9 bmdma_cmd_writeb #10 bmdma_write #11 memory_region_write_accessor #12 access_with_adjusted_size #15 flatview_write #16 address_space_write #17 address_space_rw #18 kvm_handle_io #19 kvm_cpu_exec #20 qemu_kvm_cpu_thread_fn #21 qemu_thread_start #22 start_thread #23 clone () Printing mutex in fr 2, I see "__owner = 145411", so thr2 wants aio context mutex, which is owned by thr1. Classic dead-lock. Then, let's check that aio context is hold by mirror coroutine: just print coroutine stack of first tracked request in mirror job target: (gdb) [...] (gdb) qemu coroutine 0x561035dd0860 #0 qemu_coroutine_switch #1 qemu_coroutine_yield #2 qemu_co_mutex_lock_slowpath #3 qemu_co_mutex_lock #4 qcow2_co_pwritev #5 bdrv_driver_pwritev #6 bdrv_aligned_pwritev #7 bdrv_co_pwritev #8 blk_co_pwritev #9 mirror_read_complete () at block/mirror.c:232 #10 mirror_co_read () at block/mirror.c:370 #11 coroutine_trampoline #12 __start_context Yes it is mirror_read_complete calling blk_co_pwritev after acquiring aio context. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch adds the missing checksum calculation on normal DMA transfer.
According to the datasheet this is how the SMC should behave.
Verified on AST1250 that the hardware matches the behaviour.
Signed-off-by: Christian Svensson bluecmd@google.com