CVS commit: src/sys/dev/dkwedge

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sat Apr 22 13:11:50 UTC 2023

Modified Files:
        src/sys/dev/dkwedge: dk.c

Log Message:
dk(4): Convert tests to assertions in various devsw operations.

.d_cancel, .d_strategy, .d_read, .d_write, .d_ioctl, and .d_discard
are only ever used between successful .d_open return and entry to
.d_close.  .d_open doesn't return until sc is nonnull and sc_state is
RUNNING, and dkwedge_detach waits for the last .d_close before
setting sc_state to DEAD.  So there is no possibility for sc to be
null or for sc_state to be anything other than RUNNING or DYING.

There is a small functional change here but only in the event of a
race: in the short window between when dkwedge_detach is entered, and
when .d_close runs, any I/O operations (read, write, ioctl, &c.) may
be issued that would have failed with ENXIO before.

This shouldn't matter for anything: disk I/O operations are supposed
to complete reasonably promptly, and these operations _could_ have
begun milliseconds prior, before dkwedge_detach was entered, so it's
not a significant distinction.

Notes:

- .d_open must still contend with trying to open a nonexistent wedge,
  of course.

- .d_close must also contend with closing a nonexistent wedge, in
  case there were two calls to open in quick succession and the first
  failed while the second hadn't yet determined it would fail.

- .d_size and .d_dump are used from ddb without any open/close.


To generate a diff of this commit:
cvs rdiff -u -r1.149 -r1.150 src/sys/dev/dkwedge/dk.c

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