CVS commit: src/sys/dev/pci/ixgbe

["Kengo NAKAHARA" <knakahara%netbsd.org@localhost>]

Module Name:    src
Committed By:   knakahara
Date:           Mon Sep  7 09:14:54 UTC 2020

Modified Files:
        src/sys/dev/pci/ixgbe: ixgbe.c

Log Message:
Fix race between ixgbe_msix_admin() and ixgbe_handle_admin(), pointed out by ozaki-r@n.o.

The race is caused by the following.
CPU#A processes workqueue, CPU#B processes admin interrupt.
    (0) one of CPUs already calls ixgbe_schedule_admin_tasklet()
        such as ixgbe_handle_timer()
    (1) CPU#A: read adapter->task_requests
    (2) CPU#B: set adapter->task_requests
    (3) CPU#B: read(and try to set) adapter->admin_pending
               but adapter->admin_pending is set, so does not
               call workqueue_enqueue()
    (4) CPU#A: clear adapter->admin_pending
that is, the tasks set by (2) is not processed as missfire workqueue by (3).


To generate a diff of this commit:
cvs rdiff -u -r1.257 -r1.258 src/sys/dev/pci/ixgbe/ixgbe.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.