git: 932df0a25861 - stable/13 - nvme: Remove pause while resetting

The branch stable/13 has been updated by mav:

URL: https://cgit.FreeBSD.org/src/commit/?id=932df0a258617a8b22001e1d213826b3549d6e46

commit 932df0a258617a8b22001e1d213826b3549d6e46
Author:     Warner Losh <imp@FreeBSD.org>
AuthorDate: 2021-10-01 17:09:05 +0000
Commit:     Alexander Motin <mav@FreeBSD.org>
CommitDate: 2022-01-21 02:07:30 +0000

    nvme: Remove pause while resetting
    
    After some study of the code and the standard, I think we can just drop
    the pause(), unconditionally.  If we're not initialized, then there's
    nothing to wait for from a software perspective.  If we are initialized,
    then there might be outstanding I/O. If so, then the qpair 'recovery
    state' will transition to WAITING in nvme_ctrlr_disable_qpairs, which
    will ignore any interrupts for items that complete before we complete
    the reset by setting cc.en=0.
    
    If we go on to fail the controller, we'll cancel the outstanding I/O
    transactions.  If we reset the controller, the hardware throws away
    pending transactions and we retry all the pending I/O transactions. Any
    transactions that happend to complete before cc.en=0 will have the same
    effect in the end (doing the same transaction twice is just inefficient,
    it won't affect the state of the device any differently than having done
    it once).
    
    The standard imposes no wait times here, so it isn't needed from that
    perspective.
    
    Unanswered Question: Do we may need to disable interrupts while we
    disable in legacy mode since those are level-sensitive.
    
    Sponsored by:           Netflix
    Reviewed by:            mav
    Differential Revision:  https://reviews.freebsd.org/D32248
    
    (cherry picked from commit e5e26e4a24a1142e02a9b477877e13ed0c194f36)
---
 sys/dev/nvme/nvme_ctrlr.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/sys/dev/nvme/nvme_ctrlr.c b/sys/dev/nvme/nvme_ctrlr.c
index eb95fa33b90b..d0be0da39902 100644
--- a/sys/dev/nvme/nvme_ctrlr.c
+++ b/sys/dev/nvme/nvme_ctrlr.c
@@ -410,13 +410,13 @@ nvme_ctrlr_hw_reset(struct nvme_controller *ctrlr)
 	int err;
 
 	TSENTER();
-	nvme_ctrlr_disable_qpairs(ctrlr);
 
-	pause("nvmehwreset", hz / 10);
+	nvme_ctrlr_disable_qpairs(ctrlr);
 
 	err = nvme_ctrlr_disable(ctrlr);
 	if (err != 0)
 		return err;
+
 	err = nvme_ctrlr_enable(ctrlr);
 	TSEXIT();
 	return (err);
@@ -1653,13 +1653,10 @@ nvme_ctrlr_suspend(struct nvme_controller *ctrlr)
 	 * flushes any metadata the drive may have stored so it can survive
 	 * having its power removed and prevents the unsafe shutdown count from
 	 * incriminating. Once we delete the qpairs, we have to disable them
-	 * before shutting down. The delay is out of paranoia in
-	 * nvme_ctrlr_hw_reset, and is repeated here (though we should have no
-	 * pending I/O that the delay copes with).
+	 * before shutting down.
 	 */
 	nvme_ctrlr_delete_qpairs(ctrlr);
 	nvme_ctrlr_disable_qpairs(ctrlr);
-	pause("nvmesusp", hz / 10);
 	nvme_ctrlr_shutdown(ctrlr);
 
 	return (0);