param: simple locking for sysfs-writable charp parameters
Since the writing to sysfs can free the old one, we need to block that
when we access the charp variables.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Dan Williams <dcbw@redhat.com>
Cc: John W. Linville <linville@tuxdriver.com>
Cc: Jing Huang <huangj@brocade.com>
Cc: James E.J. Bottomley <James.Bottomley@suse.de>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: libertas-dev@lists.infradead.org
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: linux-usb@vger.kernel.org
diff --git a/arch/um/drivers/hostaudio_kern.c b/arch/um/drivers/hostaudio_kern.c
index 68142df..0c46e39 100644
--- a/arch/um/drivers/hostaudio_kern.c
+++ b/arch/um/drivers/hostaudio_kern.c
@@ -187,7 +187,9 @@
int ret;
#ifdef DEBUG
+ kparam_block_sysfs_write(dsp);
printk(KERN_DEBUG "hostaudio: open called (host: %s)\n", dsp);
+ kparam_unblock_sysfs_write(dsp);
#endif
state = kmalloc(sizeof(struct hostaudio_state), GFP_KERNEL);
@@ -199,9 +201,11 @@
if (file->f_mode & FMODE_WRITE)
w = 1;
+ kparam_block_sysfs_write(dsp);
lock_kernel();
ret = os_open_file(dsp, of_set_rw(OPENFLAGS(), r, w), 0);
unlock_kernel();
+ kparam_unblock_sysfs_write(dsp);
if (ret < 0) {
kfree(state);
@@ -258,13 +262,17 @@
if (file->f_mode & FMODE_WRITE)
w = 1;
+ kparam_block_sysfs_write(mixer);
lock_kernel();
ret = os_open_file(mixer, of_set_rw(OPENFLAGS(), r, w), 0);
unlock_kernel();
+ kparam_unblock_sysfs_write(mixer);
if (ret < 0) {
+ kparam_block_sysfs_write(dsp);
printk(KERN_ERR "hostaudio_open_mixdev failed to open '%s', "
"err = %d\n", dsp, -ret);
+ kparam_unblock_sysfs_write(dsp);
kfree(state);
return ret;
}
@@ -320,8 +328,10 @@
static int __init hostaudio_init_module(void)
{
+ __kernel_param_lock();
printk(KERN_INFO "UML Audio Relay (host dsp = %s, host mixer = %s)\n",
dsp, mixer);
+ __kernel_param_unlock();
module_data.dev_audio = register_sound_dsp(&hostaudio_fops, -1);
if (module_data.dev_audio < 0) {