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

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/video/vt8623fb.c b/drivers/video/vt8623fb.c
index d31dc96f838a..85d76ec4c63e 100644
--- a/drivers/video/vt8623fb.c
+++ b/drivers/video/vt8623fb.c
@@ -726,7 +726,9 @@ static int __devinit vt8623_pci_probe(struct pci_dev *dev, const struct pci_devi
 
         /* Prepare startup mode */
 
+        kparam_block_sysfs_write(mode_option);
         rc = fb_find_mode(&(info->var), info, mode_option, NULL, 0, NULL, 8);
+        kparam_unblock_sysfs_write(mode_option);
         if (! ((rc == 1) || (rc == 2))) {
                 rc = -EINVAL;
                 dev_err(info->device, "mode %s not found\n", mode_option);