[Qemu-commits] [qemu/qemu] ae6d91: nbd/server: do not poll within a coroutine context

[Richard Henderson]

  Branch: refs/heads/staging
  Home:   https://github.com/qemu/qemu
  Commit: ae6d91a7e9b77abb029ed3fa9fad461422286942
      
https://github.com/qemu/qemu/commit/ae6d91a7e9b77abb029ed3fa9fad461422286942
  Author: Zhu Yangyang <zhuyangyang14@huawei.com>
  Date:   2024-04-25 (Thu, 25 Apr 2024)

  Changed paths:
    M nbd/client.c
    M nbd/common.c
    M nbd/nbd-internal.h
    M nbd/server.c

  Log Message:
  -----------
  nbd/server: do not poll within a coroutine context

Coroutines are not supposed to block. Instead, they should yield.

The client performs TLS upgrade outside of an AIOContext, during
synchronous handshake; this still requires g_main_loop.  But the
server responds to TLS upgrade inside a coroutine, so a nested
g_main_loop is wrong.  Since the two callbacks no longer share more
than the setting of data.complete and data.error, it's just as easy to
use static helpers instead of trying to share a common code path.  It
is also possible to add assertions that no other code is interfering
with the eventual path to qio reaching the callback, whether or not it
required a yield or main loop.

Fixes: f95910f ("nbd: implement TLS support in the protocol negotiation")
Signed-off-by: Zhu Yangyang <zhuyangyang14@huawei.com>
[eblake: move callbacks to their use point, add assertions]
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20240408160214.1200629-5-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>


  Commit: 4fa333e08dd96395a99ea8dd9e4c73a29dd23344
      
https://github.com/qemu/qemu/commit/4fa333e08dd96395a99ea8dd9e4c73a29dd23344
  Author: Eric Blake <eblake@redhat.com>
  Date:   2024-04-25 (Thu, 25 Apr 2024)

  Changed paths:
    M nbd/server.c

  Log Message:
  -----------
  nbd/server: Mark negotiation functions as coroutine_fn

nbd_negotiate() is already marked coroutine_fn.  And given the fix in
the previous patch to have nbd_negotiate_handle_starttls not create
and wait on a g_main_loop (as that would violate coroutine
constraints), it is worth marking the rest of the related static
functions reachable only during option negotiation as also being
coroutine_fn.

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20240408160214.1200629-6-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
[eblake: drop one spurious coroutine_fn marking]
Signed-off-by: Eric Blake <eblake@redhat.com>


  Commit: 77bcaf5f222fb19667738dc2ca7dec6172d69db7
      
https://github.com/qemu/qemu/commit/77bcaf5f222fb19667738dc2ca7dec6172d69db7
  Author: Richard Henderson <richard.henderson@linaro.org>
  Date:   2024-04-26 (Fri, 26 Apr 2024)

  Changed paths:
    M nbd/client.c
    M nbd/common.c
    M nbd/nbd-internal.h
    M nbd/server.c

  Log Message:
  -----------
  Merge tag 'pull-nbd-2024-04-25' of https://repo.or.cz/qemu/ericb into staging

NBD patches for 2024-04-25

- Avoid calling poll() within coroutine

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* tag 'pull-nbd-2024-04-25' of https://repo.or.cz/qemu/ericb:
  nbd/server: Mark negotiation functions as coroutine_fn
  nbd/server: do not poll within a coroutine context

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>


Compare: https://github.com/qemu/qemu/compare/a118c4aff408...77bcaf5f222f

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