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Fix a possible race condition in spc_msgin() in NO_MANUAL_XFER case. 

To avoid the race, check SSTS and INTS after XFR command as
spc_pio_datain() does.

Reported from isaki@, observed on nono emulator.
This commit is contained in:
tsutsui 2021-03-06 05:37:18 +00:00
parent f760bcae1f
commit 51975443b7
1 changed files with 10 additions and 3 deletions
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13
sys/dev/ic/mb89352.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: mb89352.c,v 1.57 2018/09/03 16:29:31 riastradh Exp $ */
/* $NetBSD: mb89352.c,v 1.58 2021/03/06 05:37:18 tsutsui Exp $ */
/* NecBSD: mb89352.c,v 1.4 1998/03/14 07:31:20 kmatsuda Exp */
/*-
@ -77,7 +77,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: mb89352.c,v 1.57 2018/09/03 16:29:31 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: mb89352.c,v 1.58 2021/03/06 05:37:18 tsutsui Exp $");
#ifdef DDB
#define integrate
@ -932,6 +932,7 @@ nextbyte:
*/
for (;;) {
#ifdef NO_MANUAL_XFER /* XXX */
uint8_t intstat;
if (bus_space_read_1(iot, ioh, INTS) != 0) {
/*
* Target left MESSAGE IN, probably because it
@ -960,12 +961,18 @@ nextbyte:
#else
bus_space_write_1(iot, ioh, SCMD, SCMD_XFR | SCMD_PROG_XFR);
#endif
intstat = 0;
for (;;) {
if ((bus_space_read_1(iot, ioh, SSTS) &
SSTS_DREG_EMPTY) == 0)
break;
if (bus_space_read_1(iot, ioh, INTS) != 0)
/*
* We have to read INTS before checking SSTS to avoid
* race between SSTS_DREG_EMPTY and INTS_CMD_DONE.
*/
if (intstat != 0)
goto out;
intstat = bus_space_read_1(iot, ioh, INTS);
}
msg = bus_space_read_1(iot, ioh, DREG);
#else