s390/ap: introduce mutex to lock the AP bus scan

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Rework the invocations around ap_scan_bus():
- Protect ap_scan_bus() with a mutex to make sure only one
  scan at a time is running.
- The workqueue invocation which is triggered by either the
  module init or via AP bus scan timer expiration uses this
  mutex and if there is already a scan running, the work
  is simple aborted (as the job is done by another task).
- The ap_bus_force_rescan() which is invoked by higher level
  layers mostly on failures which indicate a bus scan may
  help is reworked to call ap_scan_bus() direct instead of
  enqueuing work into a system workqueue and waiting for that
  to finish. Of course the mutex is respected and in case of
  another task already running a bus scan the shortcut of
  waiting for this scan to finish and reusing the scan result
  is taken.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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This commit is contained in:

Harald Freudenberger 2024-01-30 17:42:50 +01:00 • committed by Heiko Carstens

parent b5caf05ee8

commit eacf5b3651

2 changed files with 58 additions and 11 deletions

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69

drivers/s390/crypto/ap_bus.c

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2

drivers/s390/crypto/ap_bus.h

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