From: Miche Baker-Harvey <miche@google.com>
To: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
xen-devel@lists.xensource.com,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Rusty Russell <rusty@rustcorp.com.au>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Anton Blanchard <anton@samba.org>,
Amit Shah <amit.shah@redhat.com>,
Mike Waychison <mikew@google.com>,
ppc-dev <linuxppc-dev@lists.ozlabs.org>,
Eric Northrup <digitaleric@google.com>
Subject: [PATCH v3 2/3] hvc_init(): Enforce one-time initialization.
Date: Tue, 08 Nov 2011 13:45:04 -0800 [thread overview]
Message-ID: <20111108214504.28884.61814.stgit@miche.sea.corp.google.com> (raw)
In-Reply-To: <20111108214452.28884.14840.stgit@miche.sea.corp.google.com>
hvc_init() must only be called once, and no thread should continue with hvc_alloc()
until after initialization is complete. The original code does not enforce either
of these requirements. A new mutex limits entry to hvc_init() to a single thread,
and blocks all later comers until it has completed.
This patch fixes multiple crash symptoms.
Signed-off-by: Miche Baker-Harvey <miche@google.com>
---
drivers/tty/hvc/hvc_console.c | 13 +++++++++++--
1 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c
index b6b2d18..09a6159 100644
--- a/drivers/tty/hvc/hvc_console.c
+++ b/drivers/tty/hvc/hvc_console.c
@@ -29,8 +29,9 @@
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/list.h>
-#include <linux/module.h>
#include <linux/major.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/sysrq.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
@@ -84,6 +85,10 @@ static LIST_HEAD(hvc_structs);
* list traversal.
*/
static DEFINE_SPINLOCK(hvc_structs_lock);
+/*
+ * only one task does allocation at a time.
+ */
+static DEFINE_MUTEX(hvc_ports_mutex);
/*
* This value is used to assign a tty->index value to a hvc_struct based
@@ -825,11 +830,15 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
int i;
/* We wait until a driver actually comes along */
+ mutex_lock(&hvc_ports_mutex);
if (!hvc_driver) {
int err = hvc_init();
- if (err)
+ if (err) {
+ mutex_unlock(&hvc_ports_mutex);
return ERR_PTR(err);
+ }
}
+ mutex_unlock(&hvc_ports_mutex);
hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
GFP_KERNEL);
next prev parent reply other threads:[~2011-11-08 21:45 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-08 21:44 [PATCH RFC v3 0/3] Support multiple VirtioConsoles Miche Baker-Harvey
2011-11-08 21:44 ` [PATCH v3 1/3] virtio_console: Fix locking of vtermno Miche Baker-Harvey
2011-11-11 4:27 ` Rusty Russell
2011-11-17 19:09 ` Amit Shah
2011-11-08 21:45 ` Miche Baker-Harvey [this message]
2011-11-09 7:24 ` [PATCH v3 2/3] hvc_init(): Enforce one-time initialization Michael Ellerman
2011-11-11 4:30 ` Rusty Russell
2011-11-17 18:57 ` Miche Baker-Harvey
2011-11-21 5:01 ` Rusty Russell
2011-11-21 22:16 ` Miche Baker-Harvey
2011-11-22 0:58 ` Rusty Russell
2011-11-23 10:38 ` Amit Shah
2011-11-23 12:56 ` Amit Shah
2011-11-23 13:06 ` Sasha Levin
2011-11-23 13:15 ` Amit Shah
2011-11-28 23:40 ` Miche Baker-Harvey
2011-11-29 14:21 ` Amit Shah
2011-11-29 17:04 ` Miche Baker-Harvey
2011-11-29 17:50 ` Miche Baker-Harvey
2011-12-05 10:54 ` Amit Shah
2011-12-06 17:05 ` Miche Baker-Harvey
2011-12-08 12:08 ` Amit Shah
2011-12-12 19:11 ` Miche Baker-Harvey
2011-12-12 19:25 ` Amit Shah
2011-12-16 6:00 ` Amit Shah
2011-11-08 21:45 ` [PATCH v3 3/3] Use separate struct console structure for each hvc_console Miche Baker-Harvey
2011-11-09 8:05 ` Michael Ellerman
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