PR/56403 CVS commit: src/sys/dev

["Rin Okuyama" <rin%netbsd.org@localhost>]

The following reply was made to PR kern/56403; it has been noted by GNATS.

From: "Rin Okuyama" <rin%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/56403 CVS commit: src/sys/dev
Date: Tue, 5 Oct 2021 08:01:06 +0000

 Module Name:	src
 Committed By:	rin
 Date:		Tue Oct  5 08:01:05 UTC 2021
 
 Modified Files:
 	src/sys/dev/ata: ata.c ata_wdc.c atavar.h
 	src/sys/dev/ic: ahcisata_core.c mvsata.c siisata.c wdc.c
 	src/sys/dev/scsipi: atapi_wdc.c
 
 Log Message:
 PR kern/56403
 
 Fix kernel freeze for wdc(4) variants with ATAC_CAP_NOIRQ:
 
 (1) Change ata_xfer_ops:c_poll from void to int function. When it returns
     ATAPOLL_AGAIN, let ata_xfer_start() iterate itself again.
 
 (2) Let wdc_ata_bio_poll() return ATAPOLL_AGAIN until ATA_ITSDONE is
     achieved.
 
 A similar change has been made for mvsata(4) (see mvsata_bio_poll()),
 and no functional changes for other devices.
 
 This is how the drivers worked before jdolecek-ncq branch was merged.
 
 Note that this changes are less likely to cause infinite recursion:
 
 (1) wdc_ata_bio_intr() called from wdc_ata_bio_poll() asserts ATA_ITSDONE
     in its error handling paths via wdc_ata_bio_done().
 
 (2) Return value from c_start (= wdc_ata_bio_start()) is checked in
     ata_xfer_start().
 
 Therefore, errors encountered in ata_xfer_ops:c_poll and c_start routines
 terminate the recursion for wdc(4). The situation is similar for mvsata(4).
 
 Still, there is a possibility where ata_xfer_start() takes long time to
 finish a normal operation. This can result in a delayed response for lower
 priority interrupts. But, I've never observed such a situation, even when
 heavy thrashing takes place for swap partition in wd(4).
 
 "Go ahead" by jdolecek@.
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.163 -r1.164 src/sys/dev/ata/ata.c
 cvs rdiff -u -r1.119 -r1.120 src/sys/dev/ata/ata_wdc.c
 cvs rdiff -u -r1.108 -r1.109 src/sys/dev/ata/atavar.h
 cvs rdiff -u -r1.101 -r1.102 src/sys/dev/ic/ahcisata_core.c
 cvs rdiff -u -r1.60 -r1.61 src/sys/dev/ic/mvsata.c
 cvs rdiff -u -r1.48 -r1.49 src/sys/dev/ic/siisata.c
 cvs rdiff -u -r1.307 -r1.308 src/sys/dev/ic/wdc.c
 cvs rdiff -u -r1.140 -r1.141 src/sys/dev/scsipi/atapi_wdc.c
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.