CVS commit: src/sys/dev/pci

[Christos Zoulas]

Module Name:    src
Committed By:   christos
Date:           Sun May 24 22:03:02 UTC 2015

Modified Files:
        src/sys/dev/pci: auich.c

Log Message:
PR/49926: Robert Millan: Avoid deadlock condition in auich_read_codec()
and auich_write_codec() when running in userspase.


To generate a diff of this commit:
cvs rdiff -u -r1.147 -r1.148 src/sys/dev/pci/auich.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/pci/auich.c
diff -u src/sys/dev/pci/auich.c:1.147 src/sys/dev/pci/auich.c:1.148
--- src/sys/dev/pci/auich.c:1.147	Sun May 24 10:56:57 2015
+++ src/sys/dev/pci/auich.c	Sun May 24 18:03:02 2015
@@ -1,4 +1,4 @@
-/*	$NetBSD: auich.c,v 1.147 2015/05/24 14:56:57 christos Exp $	*/
+/*	$NetBSD: auich.c,v 1.148 2015/05/24 22:03:02 christos Exp $	*/
 
 /*-
  * Copyright (c) 2000, 2004, 2005, 2008 The NetBSD Foundation, Inc.
@@ -111,7 +111,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: auich.c,v 1.147 2015/05/24 14:56:57 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: auich.c,v 1.148 2015/05/24 22:03:02 christos Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -233,6 +233,8 @@ struct auich_softc {
 	struct audio_format sc_modem_formats[AUICH_MODEM_NFORMATS];
 	struct audio_encoding_set *sc_encodings;
 	struct audio_encoding_set *sc_spdif_encodings;
+
+	int sc_cas_been_used;
 };
 
 /* Debug */
@@ -788,6 +790,18 @@ auich_read_codec(void *v, uint8_t reg, u
 		ICH_CAS + sc->sc_modem_offset) & 1;
 	    DELAY(ICH_CODECIO_INTERVAL));
 
+	/*
+	 * Be permissive in first attempt. If previous instances of
+	 * this routine were interrupted precisely at this point (after
+	 * access is granted by CAS but before a command is sent),
+	 * they could have left hardware in an inconsistent state where
+	 * a command is expected and therefore semaphore wait would hit
+	 * the timeout.
+	 */
+	if (!sc->sc_cas_been_used && i <= 0)
+		i = 1;
+	sc->sc_cas_been_used = 1;
+
 	if (i > 0) {
 		*val = bus_space_read_2(sc->iot, sc->mix_ioh,
 		    reg + (sc->sc_codecnum * ICH_CODEC_OFFSET));
@@ -832,6 +846,11 @@ auich_write_codec(void *v, uint8_t reg, 
 		ICH_CAS + sc->sc_modem_offset) & 1;
 	    DELAY(ICH_CODECIO_INTERVAL));
 
+	/* Be permissive in first attempt (see comments in auich_read_codec) */
+	if (!sc->sc_cas_been_used && i <= 0)
+		i = 1;
+	sc->sc_cas_been_used = 1;
+
 	if (i > 0) {
 		bus_space_write_2(sc->iot, sc->mix_ioh,
 		    reg + (sc->sc_codecnum * ICH_CODEC_OFFSET), val);