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Gui-Dong Han
7ddb521ab0
Move the stuck SRQ state update into autopoll_all_devices() and keep it
under big_gpib_mutex. Except for initialization, keep the stuck_srq users
under this mutex.
autopoll_all_devices() is only called by autospoll_thread(), so there is
no need to return to autospoll_thread() and set this state after dropping
big_gpib_mutex.
Without the mutex, a newly opened device can clear stuck_srq and have
that clear overwritten by the previous autospoll result:
autospoll: serial_poll_all() returns 0 and unlocks big_gpib_mutex
open_dev_ioctl: open new device and clear stuck_srq
with big_gpib_mutex held
autospoll: set stuck_srq
That leaves the board marked stuck again after the new device is opened.
autospoll_wait_should_wake_up() then refuses to poll while stuck_srq is
set, so later SRQ handling can be mistakenly suppressed.
Without the mutex, atomic_set() and set_bit() only make individual
updates atomic. They do not order the two updates or make stuck_srq and
status visible as a consistent pair. Taking big_gpib_mutex serializes the
state transition with the other runtime users.
Keep the existing wakeup behavior unchanged and only move the stuck SRQ
state update under the mutex.
Fixes: 9dde4559e9 ("staging: gpib: Add GPIB common core driver")
Signed-off-by: Gui-Dong Han <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>