[media] dvb: push down ioctl lock in dvb_usercopy

Since most dvb ioctls wrap their real work with dvb_usercopy, the static mutex
used in dvb_usercopy effectively is a global lock for dvb ioctls.
Unfortunately, frontend ioctls can be blocked by the frontend thread for
several seconds; this leads to unacceptable lock contention.  Mitigate that by
pushing the mutex from dvb_usercopy down to the individual, device specific
ioctls.
There are 10 such ioctl functions using dvb_usercopy, either calling it
directly, or via the trivial wrapper dvb_generic_ioctl. The following already
employ their own locking and look safe:
    • dvb_demux_ioctl           (as per dvb_demux_do_ioctl)
    • dvb_dvr_ioctl             (as per dvb_dvr_do_ioctl)
    • dvb_osd_ioctl             (as per single non-trivial callee)
    • fdtv_ca_ioctl             (as per callees)
    • dvb_frontend_ioctl
The following functions do not, and are thus changed to use a device specific
mutex:
    • dvb_net_ioctl             (as per dvb_net_do_ioctl)
    • dvb_ca_en50221_io_ioctl   (as per dvb_ca_en50221_io_do_ioctl)
    • dvb_video_ioctl
    • dvb_audio_ioctl
    • dvb_ca_ioctl

Signed-off-by: Nikolaus Schulz <schulz@macnetix.de>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

8 files changed, 87 insertions, 32 deletions

diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb-core/dvb_ca_en50221.c
index 9be65a3b931f..190e5e0f48c7 100644
--- a/drivers/media/dvb-core/dvb_ca_en50221.c
+++ b/drivers/media/dvb-core/dvb_ca_en50221.c
@@ -156,6 +156,9 @@ struct dvb_ca_private {
 
         /* Slot to start looking for data to read from in the next user-space read operation */
         int next_read_slot;
+
+        /* mutex serializing ioctls */
+        struct mutex ioctl_mutex;
 };
 
 static void dvb_ca_en50221_thread_wakeup(struct dvb_ca_private *ca);
@@ -1191,6 +1194,9 @@ static int dvb_ca_en50221_io_do_ioctl(struct file *file,
 
         dprintk("%s\n", __func__);
 
+        if (mutex_lock_interruptible(&ca->ioctl_mutex))
+                return -ERESTARTSYS;
+
         switch (cmd) {
         case CA_RESET:
                 for (slot = 0; slot < ca->slot_count; slot++) {
@@ -1241,6 +1247,7 @@ static int dvb_ca_en50221_io_do_ioctl(struct file *file,
                 break;
         }
 
+        mutex_unlock(&ca->ioctl_mutex);
         return err;
 }
 
@@ -1695,6 +1702,8 @@ int dvb_ca_en50221_init(struct dvb_adapter *dvb_adapter,
                 mutex_init(&ca->slot_info[i].slot_lock);
         }
 
+        mutex_init(&ca->ioctl_mutex);
+
         if (signal_pending(current)) {
                 ret = -EINTR;
                 goto error;
diff --git a/drivers/media/dvb-core/dvb_net.c b/drivers/media/dvb-core/dvb_net.c
index c2117688aa23..44225b186f6d 100644
--- a/drivers/media/dvb-core/dvb_net.c
+++ b/drivers/media/dvb-core/dvb_net.c
@@ -1345,26 +1345,35 @@ static int dvb_net_do_ioctl(struct file *file,
 {
         struct dvb_device *dvbdev = file->private_data;
         struct dvb_net *dvbnet = dvbdev->priv;
+        int ret = 0;
 
         if (((file->f_flags&O_ACCMODE)==O_RDONLY))
                 return -EPERM;
 
+        if (mutex_lock_interruptible(&dvbnet->ioctl_mutex))
+                return -ERESTARTSYS;
+
         switch (cmd) {
         case NET_ADD_IF:
         {
                 struct dvb_net_if *dvbnetif = parg;
                 int result;
 
-                if (!capable(CAP_SYS_ADMIN))
-                        return -EPERM;
+                if (!capable(CAP_SYS_ADMIN)) {
+                        ret = -EPERM;
+                        goto ioctl_error;
+                }
 
-                if (!try_module_get(dvbdev->adapter->module))
-                        return -EPERM;
+                if (!try_module_get(dvbdev->adapter->module)) {
+                        ret = -EPERM;
+                        goto ioctl_error;
+                }
 
                 result=dvb_net_add_if(dvbnet, dvbnetif->pid, dvbnetif->feedtype);
                 if (result<0) {
                         module_put(dvbdev->adapter->module);
-                        return result;
+                        ret = result;
+                        goto ioctl_error;
                 }
                 dvbnetif->if_num=result;
                 break;
@@ -1376,8 +1385,10 @@ static int dvb_net_do_ioctl(struct file *file,
                 struct dvb_net_if *dvbnetif = parg;
 
                 if (dvbnetif->if_num >= DVB_NET_DEVICES_MAX ||
-                    !dvbnet->state[dvbnetif->if_num])
-                        return -EINVAL;
+                    !dvbnet->state[dvbnetif->if_num]) {
+                        ret = -EINVAL;
+                        goto ioctl_error;
+                }
 
                 netdev = dvbnet->device[dvbnetif->if_num];
 
@@ -1388,16 +1399,18 @@ static int dvb_net_do_ioctl(struct file *file,
         }
         case NET_REMOVE_IF:
         {
-                int ret;
-
-                if (!capable(CAP_SYS_ADMIN))
-                        return -EPERM;
-                if ((unsigned long) parg >= DVB_NET_DEVICES_MAX)
-                        return -EINVAL;
+                if (!capable(CAP_SYS_ADMIN)) {
+                        ret = -EPERM;
+                        goto ioctl_error;
+                }
+                if ((unsigned long) parg >= DVB_NET_DEVICES_MAX) {
+                        ret = -EINVAL;
+                        goto ioctl_error;
+                }
                 ret = dvb_net_remove_if(dvbnet, (unsigned long) parg);
                 if (!ret)
                         module_put(dvbdev->adapter->module);
-                return ret;
+                break;
         }
 
         /* binary compatibility cruft */
@@ -1406,16 +1419,21 @@ static int dvb_net_do_ioctl(struct file *file,
                 struct __dvb_net_if_old *dvbnetif = parg;
                 int result;
 
-                if (!capable(CAP_SYS_ADMIN))
-                        return -EPERM;
+                if (!capable(CAP_SYS_ADMIN)) {
+                        ret = -EPERM;
+                        goto ioctl_error;
+                }
 
-                if (!try_module_get(dvbdev->adapter->module))
-                        return -EPERM;
+                if (!try_module_get(dvbdev->adapter->module)) {
+                        ret = -EPERM;
+                        goto ioctl_error;
+                }
 
                 result=dvb_net_add_if(dvbnet, dvbnetif->pid, DVB_NET_FEEDTYPE_MPE);
                 if (result<0) {
                         module_put(dvbdev->adapter->module);
-                        return result;
+                        ret = result;
+                        goto ioctl_error;
                 }
                 dvbnetif->if_num=result;
                 break;
@@ -1427,8 +1445,10 @@ static int dvb_net_do_ioctl(struct file *file,
                 struct __dvb_net_if_old *dvbnetif = parg;
 
                 if (dvbnetif->if_num >= DVB_NET_DEVICES_MAX ||
-                    !dvbnet->state[dvbnetif->if_num])
-                        return -EINVAL;
+                    !dvbnet->state[dvbnetif->if_num]) {
+                        ret = -EINVAL;
+                        goto ioctl_error;
+                }
 
                 netdev = dvbnet->device[dvbnetif->if_num];
 
@@ -1437,9 +1457,13 @@ static int dvb_net_do_ioctl(struct file *file,
                 break;
         }
         default:
-                return -ENOTTY;
+                ret = -ENOTTY;
+                break;
         }
-        return 0;
+
+ioctl_error:
+        mutex_unlock(&dvbnet->ioctl_mutex);
+        return ret;
 }
 
 static long dvb_net_ioctl(struct file *file,
@@ -1505,6 +1529,7 @@ int dvb_net_init (struct dvb_adapter *adap, struct dvb_net *dvbnet,
 {
         int i;
 
+        mutex_init(&dvbnet->ioctl_mutex);
         dvbnet->demux = dmx;
 
         for (i=0; i<DVB_NET_DEVICES_MAX; i++)
diff --git a/drivers/media/dvb-core/dvb_net.h b/drivers/media/dvb-core/dvb_net.h
index 1e53acd50cf4..ede78e8c8aa8 100644
--- a/drivers/media/dvb-core/dvb_net.h
+++ b/drivers/media/dvb-core/dvb_net.h
@@ -40,6 +40,7 @@ struct dvb_net {
         int state[DVB_NET_DEVICES_MAX];
         unsigned int exit:1;
         struct dmx_demux *demux;
+        struct mutex ioctl_mutex;
 };
 
 void dvb_net_release(struct dvb_net *);
diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c
index d33101aaf0b5..401ef64f92c6 100644
--- a/drivers/media/dvb-core/dvbdev.c
+++ b/drivers/media/dvb-core/dvbdev.c
@@ -418,10 +418,8 @@ int dvb_usercopy(struct file *file,
         }
 
         /* call driver */
-        mutex_lock(&dvbdev_mutex);
         if ((err = func(file, cmd, parg)) == -ENOIOCTLCMD)
                 err = -ENOTTY;
-        mutex_unlock(&dvbdev_mutex);
 
         if (err < 0)
                 goto out;
diff --git a/drivers/media/pci/ttpci/av7110.c b/drivers/media/pci/ttpci/av7110.c
index 4bd8bd56befc..2f54e2b741f6 100644
--- a/drivers/media/pci/ttpci/av7110.c
+++ b/drivers/media/pci/ttpci/av7110.c
@@ -2723,6 +2723,8 @@ static int __devinit av7110_attach(struct saa7146_dev* dev,
         if (ret < 0)
                 goto err_av7110_exit_v4l_12;
 
+        mutex_init(&av7110->ioctl_mutex);
+
 #if defined(CONFIG_INPUT_EVDEV) || defined(CONFIG_INPUT_EVDEV_MODULE)
         av7110_ir_init(av7110);
 #endif
diff --git a/drivers/media/pci/ttpci/av7110.h b/drivers/media/pci/ttpci/av7110.h
index a378662b1dcf..ef3d9606b269 100644
--- a/drivers/media/pci/ttpci/av7110.h
+++ b/drivers/media/pci/ttpci/av7110.h
@@ -271,6 +271,8 @@ struct av7110 {
         struct dvb_frontend* fe;
         fe_status_t fe_status;
 
+        struct mutex ioctl_mutex;
+
         /* crash recovery */
         void                            (*recover)(struct av7110* av7110);
         fe_sec_voltage_t                saved_voltage;
diff --git a/drivers/media/pci/ttpci/av7110_av.c b/drivers/media/pci/ttpci/av7110_av.c
index 952b33dbac4f..301029ca4535 100644
--- a/drivers/media/pci/ttpci/av7110_av.c
+++ b/drivers/media/pci/ttpci/av7110_av.c
@@ -1109,6 +1109,9 @@ static int dvb_video_ioctl(struct file *file,
                 }
         }
 
+        if (mutex_lock_interruptible(&av7110->ioctl_mutex))
+                return -ERESTARTSYS;
+
         switch (cmd) {
         case VIDEO_STOP:
                 av7110->videostate.play_state = VIDEO_STOPPED;
@@ -1297,6 +1300,7 @@ static int dvb_video_ioctl(struct file *file,
                 break;
         }
 
+        mutex_unlock(&av7110->ioctl_mutex);
         return ret;
 }
 
@@ -1314,6 +1318,9 @@ static int dvb_audio_ioctl(struct file *file,
             (cmd != AUDIO_GET_STATUS))
                 return -EPERM;
 
+        if (mutex_lock_interruptible(&av7110->ioctl_mutex))
+                return -ERESTARTSYS;
+
         switch (cmd) {
         case AUDIO_STOP:
                 if (av7110->audiostate.stream_source == AUDIO_SOURCE_MEMORY)
@@ -1442,6 +1449,7 @@ static int dvb_audio_ioctl(struct file *file,
                 ret = -ENOIOCTLCMD;
         }
 
+        mutex_unlock(&av7110->ioctl_mutex);
         return ret;
 }
 
diff --git a/drivers/media/pci/ttpci/av7110_ca.c b/drivers/media/pci/ttpci/av7110_ca.c
index 9fc1dd0ba4c3..a6079b90252a 100644
--- a/drivers/media/pci/ttpci/av7110_ca.c
+++ b/drivers/media/pci/ttpci/av7110_ca.c
@@ -253,12 +253,17 @@ static int dvb_ca_ioctl(struct file *file, unsigned int cmd, void *parg)
         struct dvb_device *dvbdev = file->private_data;
         struct av7110 *av7110 = dvbdev->priv;
         unsigned long arg = (unsigned long) parg;
+        int ret = 0;
 
         dprintk(8, "av7110:%p\n",av7110);
 
+        if (mutex_lock_interruptible(&av7110->ioctl_mutex))
+                return -ERESTARTSYS;
+
         switch (cmd) {
         case CA_RESET:
-                return ci_ll_reset(&av7110->ci_wbuffer, file, arg, &av7110->ci_slot[0]);
+                ret = ci_ll_reset(&av7110->ci_wbuffer, file, arg,
+                                  &av7110->ci_slot[0]);
                 break;
         case CA_GET_CAP:
         {
@@ -277,8 +282,10 @@ static int dvb_ca_ioctl(struct file *file, unsigned int cmd, void *parg)
         {
                 ca_slot_info_t *info=(ca_slot_info_t *)parg;
 
-                if (info->num < 0 || info->num > 1)
+                if (info->num < 0 || info->num > 1) {
+                        mutex_unlock(&av7110->ioctl_mutex);
                         return -EINVAL;
+                }
                 av7110->ci_slot[info->num].num = info->num;
                 av7110->ci_slot[info->num].type = FW_CI_LL_SUPPORT(av7110->arm_app) ?
                                                         CA_CI_LINK : CA_CI;
@@ -306,10 +313,10 @@ static int dvb_ca_ioctl(struct file *file, unsigned int cmd, void *parg)
         {
                 ca_descr_t *descr = (ca_descr_t*) parg;
 
-                if (descr->index >= 16)
-                        return -EINVAL;
-                if (descr->parity > 1)
+                if (descr->index >= 16 || descr->parity > 1) {
+                        mutex_unlock(&av7110->ioctl_mutex);
                         return -EINVAL;
+                }
                 av7110_fw_cmd(av7110, COMTYPE_PIDFILTER, SetDescr, 5,
                               (descr->index<<8)|descr->parity,
                               (descr->cw[0]<<8)|descr->cw[1],
@@ -320,9 +327,12 @@ static int dvb_ca_ioctl(struct file *file, unsigned int cmd, void *parg)
         }
 
         default:
-                return -EINVAL;
+                ret = -EINVAL;
+                break;
         }
-        return 0;
+
+        mutex_unlock(&av7110->ioctl_mutex);
+        return ret;
 }
 
 static ssize_t dvb_ca_write(struct file *file, const char __user *buf,