OSS sequencer emulation still allows to queue and issue the events
that manipulate the client pool concurrently in a racy way. This
patch serializes the access like the normal sequencer write / ioctl
via taking the client ioctl_mutex. Since the access to the sequencer
client is done indirectly via a client id number, a new helper to
take/release the mutex is introduced.
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
sound/core/seq/oss/seq_oss_device.h | 10 ++++++++--
sound/core/seq/seq_clientmgr.c | 40 ++++++++++++++++++++++++++++++++++---
sound/core/seq/seq_clientmgr.h | 4 ++++
3 files changed, 49 insertions(+), 5 deletions(-)
diff --git a/sound/core/seq/oss/seq_oss_device.h b/sound/core/seq/oss/seq_oss_device.h
index 2d0e9eaf13aa..77eb1fe1155c 100644
--- a/sound/core/seq/oss/seq_oss_device.h
+++ b/sound/core/seq/oss/seq_oss_device.h
@@ -30,6 +30,7 @@
#include <sound/rawmidi.h>
#include <sound/seq_kernel.h>
#include <sound/info.h>
+#include "../seq_clientmgr.h"
/* max. applications */
#define SNDRV_SEQ_OSS_MAX_CLIENTS 16
@@ -150,11 +151,16 @@ snd_seq_oss_dispatch(struct seq_oss_devinfo *dp, struct snd_seq_event *ev, int a
return snd_seq_kernel_client_dispatch(dp->cseq, ev, atomic, hop);
}
-/* ioctl */
+/* ioctl for writeq */
static inline int
snd_seq_oss_control(struct seq_oss_devinfo *dp, unsigned int type, void *arg)
{
- return snd_seq_kernel_client_ctl(dp->cseq, type, arg);
+ int err;
+
+ snd_seq_client_ioctl_lock(dp->cseq);
+ err = snd_seq_kernel_client_ctl(dp->cseq, type, arg);
+ snd_seq_client_ioctl_unlock(dp->cseq);
+ return err;
}
/* fill the addresses in header */
diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
index 0af5b1440b33..a5c9d59eb5b8 100644
--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -179,6 +179,36 @@ struct snd_seq_client *snd_seq_client_use_ptr(int clientid)
return client;
}
+/* Take refcount and perform ioctl_mutex lock on the given client;
+ * used only for OSS sequencer
+ * Unlock via snd_seq_client_ioctl_unlock() below
+ */
+bool snd_seq_client_ioctl_lock(int clientid)
+{
+ struct snd_seq_client *client;
+
+ client = snd_seq_client_use_ptr(clientid);
+ if (!client)
+ return false;
+ mutex_lock(&client->ioctl_mutex);
+ return true;
+}
+EXPORT_SYMBOL_GPL(snd_seq_client_ioctl_lock);
+
+/* Unlock and unref the given client; for OSS sequencer use only */
+void snd_seq_client_ioctl_unlock(int clientid)
+{
+ struct snd_seq_client *client;
+
+ client = snd_seq_client_use_ptr(clientid);
+ if (WARN_ON(!client))
+ return;
+ mutex_unlock(&client->ioctl_mutex);
+ snd_use_lock_free(&client->use_lock);
+ snd_seq_client_unlock(client);
+}
+EXPORT_SYMBOL_GPL(snd_seq_client_ioctl_unlock);
+
static void usage_alloc(struct snd_seq_usage *res, int num)
{
res->cur += num;
@@ -2247,11 +2277,15 @@ int snd_seq_kernel_client_enqueue(int client, struct snd_seq_event *ev,
if (cptr == NULL)
return -EINVAL;
- if (! cptr->accept_output)
+ if (!cptr->accept_output) {
result = -EPERM;
- else /* send it */
+ } else { /* send it */
+ mutex_lock(&cptr->ioctl_mutex);
result = snd_seq_client_enqueue_event(cptr, ev, file, blocking,
- false, 0, NULL);
+ false, 0,
+ &cptr->ioctl_mutex);
+ mutex_unlock(&cptr->ioctl_mutex);
+ }
snd_seq_client_unlock(cptr);
return result;
diff --git a/sound/core/seq/seq_clientmgr.h b/sound/core/seq/seq_clientmgr.h
index 66ad3d547916..28a51dcc0190 100644
--- a/sound/core/seq/seq_clientmgr.h
+++ b/sound/core/seq/seq_clientmgr.h
@@ -97,6 +97,10 @@ int snd_seq_kernel_client_write_poll(int clientid, struct file *file, poll_table
int snd_seq_client_notify_subscription(int client, int port,
struct snd_seq_port_subscribe *info, int evtype);
+/* only for OSS sequencer */
+bool snd_seq_client_ioctl_lock(int clientid);
+void snd_seq_client_ioctl_unlock(int clientid);
+
extern int seq_client_load[15];
#endif
--
2.16.4
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