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

arch/um/drivers/hostaudio_kern.c

@@ -187,7 +187,9 @@ static int hostaudio_open(struct inode *inode, struct file *file)
 	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 @@ static int hostaudio_open(struct inode *inode, struct file *file)
 	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 @@ static int hostmixer_open_mixdev(struct inode *inode, struct file *file)
 	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 @@ MODULE_LICENSE("GPL");
 
 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) {

drivers/net/wireless/libertas/if_usb.c

@@ -289,10 +289,13 @@ static int if_usb_probe(struct usb_interface *intf,
 	}
 
 	/* Upload firmware */
+	kparam_block_sysfs_write(fw_name);
 	if (__if_usb_prog_firmware(cardp, lbs_fw_name, BOOT_CMD_FW_BY_USB)) {
+		kparam_unblock_sysfs_write(fw_name);
 		lbs_deb_usbd(&udev->dev, "FW upload failed\n");
 		goto err_prog_firmware;
 	}
+	kparam_unblock_sysfs_write(fw_name);
 
 	if (!(priv = lbs_add_card(cardp, &udev->dev)))
 		goto err_prog_firmware;

drivers/net/wireless/libertas_tf/if_usb.c

@@ -811,12 +811,15 @@ static int if_usb_prog_firmware(struct if_usb_card *cardp)
 
 	lbtf_deb_enter(LBTF_DEB_USB);
 
+	kparam_block_sysfs_write(fw_name);
 	ret = request_firmware(&cardp->fw, lbtf_fw_name, &cardp->udev->dev);
 	if (ret < 0) {
 		pr_err("request_firmware() failed with %#x\n", ret);
 		pr_err("firmware %s not found\n", lbtf_fw_name);
+		kparam_unblock_sysfs_write(fw_name);
 		goto done;
 	}
+	kparam_unblock_sysfs_write(fw_name);
 
 	if (check_fwfile_format(cardp->fw->data, cardp->fw->size))
 		goto release_fw;

drivers/scsi/bfa/bfad.c

@@ -788,6 +788,7 @@ bfad_drv_init(struct bfad_s *bfad)
 	memset(&driver_info, 0, sizeof(driver_info));
 	strncpy(driver_info.version, BFAD_DRIVER_VERSION,
 		sizeof(driver_info.version) - 1);
+	__kernel_param_lock();
 	if (host_name)
 		strncpy(driver_info.host_machine_name, host_name,
 			sizeof(driver_info.host_machine_name) - 1);
@@ -797,6 +798,7 @@ bfad_drv_init(struct bfad_s *bfad)
 	if (os_patch)
 		strncpy(driver_info.host_os_patch, os_patch,
 			sizeof(driver_info.host_os_patch) - 1);
+	__kernel_param_unlock();
 
 	strncpy(driver_info.os_device_name, bfad->pci_name,
 		sizeof(driver_info.os_device_name - 1));

drivers/usb/atm/ueagle-atm.c

@@ -1577,6 +1577,7 @@ static void cmvs_file_name(struct uea_softc *sc, char *const cmv_name, int ver)
 	char file_arr[] = "CMVxy.bin";
 	char *file;
 
+	kparam_block_sysfs_write(cmv_file);
 	/* set proper name corresponding modem version and line type */
 	if (cmv_file[sc->modem_index] == NULL) {
 		if (UEA_CHIP_VERSION(sc) == ADI930)
@@ -1595,6 +1596,7 @@ static void cmvs_file_name(struct uea_softc *sc, char *const cmv_name, int ver)
 	strlcat(cmv_name, file, UEA_FW_NAME_MAX);
 	if (ver == 2)
 		strlcat(cmv_name, ".v2", UEA_FW_NAME_MAX);
+	kparam_unblock_sysfs_write(cmv_file);
 }
 
 static int request_cmvs_old(struct uea_softc *sc,

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);

net/mac80211/rate.c

@@ -103,6 +103,7 @@ ieee80211_rate_control_ops_get(const char *name)
 	struct rate_control_ops *ops;
 	const char *alg_name;
 
+	kparam_block_sysfs_write(ieee80211_default_rc_algo);
 	if (!name)
 		alg_name = ieee80211_default_rc_algo;
 	else
@@ -120,6 +121,7 @@ ieee80211_rate_control_ops_get(const char *name)
 	/* try built-in one if specific alg requested but not found */
 	if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
 		ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
+	kparam_unblock_sysfs_write(ieee80211_default_rc_algo);
 
 	return ops;
 }