From 344d6c6ba6ba5c4fede2f07adbd26d53109a2dd8 Mon Sep 17 00:00:00 2001 From: Jonathan Nieder Date: Sun, 1 May 2011 06:30:14 -0300 Subject: [PATCH] [media] cx88: protect cx8802_devlist with a mutex Add and use a mutex to protect the cx88-mpeg device list. Previously the BKL prevented races. Based on work by Ben Hutchings . Tested-by: Andi Huber Tested-by: Marlon de Boer Signed-off-by: Jonathan Nieder Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/cx88/cx88-mpeg.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/drivers/media/video/cx88/cx88-mpeg.c b/drivers/media/video/cx88/cx88-mpeg.c index 455290011d4..1a7b983f829 100644 --- a/drivers/media/video/cx88/cx88-mpeg.c +++ b/drivers/media/video/cx88/cx88-mpeg.c @@ -78,6 +78,7 @@ static void flush_request_modules(struct cx8802_dev *dev) static LIST_HEAD(cx8802_devlist); +static DEFINE_MUTEX(cx8802_mutex); /* ------------------------------------------------------------------ */ static int cx8802_start_dma(struct cx8802_dev *dev, @@ -689,6 +690,8 @@ int cx8802_register_driver(struct cx8802_driver *drv) return err; } + mutex_lock(&cx8802_mutex); + list_for_each_entry(dev, &cx8802_devlist, devlist) { printk(KERN_INFO "%s/2: subsystem: %04x:%04x, board: %s [card=%d]\n", @@ -698,8 +701,10 @@ int cx8802_register_driver(struct cx8802_driver *drv) /* Bring up a new struct for each driver instance */ driver = kzalloc(sizeof(*drv),GFP_KERNEL); - if (driver == NULL) - return -ENOMEM; + if (driver == NULL) { + err = -ENOMEM; + goto out; + } /* Snapshot of the driver registration data */ drv->core = dev->core; @@ -722,7 +727,10 @@ int cx8802_register_driver(struct cx8802_driver *drv) mutex_unlock(&drv->core->lock); } - return i ? 0 : -ENODEV; + err = i ? 0 : -ENODEV; +out: + mutex_unlock(&cx8802_mutex); + return err; } int cx8802_unregister_driver(struct cx8802_driver *drv) @@ -736,6 +744,8 @@ int cx8802_unregister_driver(struct cx8802_driver *drv) drv->type_id == CX88_MPEG_DVB ? "dvb" : "blackbird", drv->hw_access == CX8802_DRVCTL_SHARED ? "shared" : "exclusive"); + mutex_lock(&cx8802_mutex); + list_for_each_entry(dev, &cx8802_devlist, devlist) { printk(KERN_INFO "%s/2: subsystem: %04x:%04x, board: %s [card=%d]\n", @@ -762,6 +772,8 @@ int cx8802_unregister_driver(struct cx8802_driver *drv) mutex_unlock(&dev->core->lock); } + mutex_unlock(&cx8802_mutex); + return err; } @@ -799,7 +811,9 @@ static int __devinit cx8802_probe(struct pci_dev *pci_dev, goto fail_free; INIT_LIST_HEAD(&dev->drvlist); + mutex_lock(&cx8802_mutex); list_add_tail(&dev->devlist,&cx8802_devlist); + mutex_unlock(&cx8802_mutex); /* now autoload cx88-dvb or cx88-blackbird */ request_modules(dev);