[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>

diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb-core/dvb_ca_en50221.c
index 9be65a3..190e5e0 100644 (file)
--- 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 c211768..44225b1 100644 (file)
--- 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 1e53acd..ede78e8 100644 (file)
--- 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 d33101a..401ef64 100644 (file)
--- 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 4bd8bd5..2f54e2b 100644 (file)
--- 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 a378662..ef3d960 100644 (file)
--- 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 952b33d..301029c 100644 (file)
--- 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 9fc1dd0..a6079b9 100644 (file)
--- 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,