Module Name: src Committed By: tsutsui Date: Sat Mar 6 05:37:18 UTC 2021
Modified Files: src/sys/dev/ic: mb89352.c Log Message: 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. To generate a diff of this commit: cvs rdiff -u -r1.57 -r1.58 src/sys/dev/ic/mb89352.c Please note that diffs are not public domain; they are subject to the copyright notices on the relevant files.
Modified files: Index: src/sys/dev/ic/mb89352.c diff -u src/sys/dev/ic/mb89352.c:1.57 src/sys/dev/ic/mb89352.c:1.58 --- src/sys/dev/ic/mb89352.c:1.57 Mon Sep 3 16:29:31 2018 +++ src/sys/dev/ic/mb89352.c Sat Mar 6 05:37:18 2021 @@ -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