ALSA: rawmidi: Move lock to snd_rawmidi_substream

Having a lock in snd_rawmidi_runtime can be a problem especially when
a substream is accessed from the outside, as the runtime creation
might be racy with the external calls.  As a first step for hardening,
move the spinlock from snd_rawmidi_runtime to snd_rawmidi_substream.

This patch just replaces the lock calls, no real functional change is
put yet.

Link: https://lore.kernel.org/r/20220617144051.18985-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/include/sound/rawmidi.h b/include/sound/rawmidi.h
index 9402c25..e1f59b2 100644 (file)
--- a/include/sound/rawmidi.h
+++ b/include/sound/rawmidi.h
@@ -63,7 +63,6 @@ struct snd_rawmidi_runtime {
        size_t xruns;           /* over/underruns counter */
        int buffer_ref;         /* buffer reference count */
        /* misc */
-       spinlock_t lock;
        wait_queue_head_t sleep;
        /* event handler (new bytes, input only) */
        void (*event)(struct snd_rawmidi_substream *substream);
@@ -85,6 +84,7 @@ struct snd_rawmidi_substream {
        unsigned int clock_type;        /* clock source to use for input framing */
        int use_count;                  /* use counter (for output) */
        size_t bytes;
+       spinlock_t lock;
        struct snd_rawmidi *rmidi;
        struct snd_rawmidi_str *pstr;
        char name[32];

diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index 82e8f65..0a00f37 100644 (file)
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -102,13 +102,12 @@ static inline bool __snd_rawmidi_ready(struct snd_rawmidi_runtime *runtime)
 
 static bool snd_rawmidi_ready(struct snd_rawmidi_substream *substream)
 {
-       struct snd_rawmidi_runtime *runtime = substream->runtime;
        unsigned long flags;
        bool ready;
 
-       spin_lock_irqsave(&runtime->lock, flags);
-       ready = __snd_rawmidi_ready(runtime);
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
+       ready = __snd_rawmidi_ready(substream->runtime);
+       spin_unlock_irqrestore(&substream->lock, flags);
        return ready;
 }
 
@@ -130,7 +129,7 @@ static void snd_rawmidi_input_event_work(struct work_struct *work)
                runtime->event(runtime->substream);
 }
 
-/* buffer refcount management: call with runtime->lock held */
+/* buffer refcount management: call with substream->lock held */
 static inline void snd_rawmidi_buffer_ref(struct snd_rawmidi_runtime *runtime)
 {
        runtime->buffer_ref++;
@@ -149,7 +148,6 @@ static int snd_rawmidi_runtime_create(struct snd_rawmidi_substream *substream)
        if (!runtime)
                return -ENOMEM;
        runtime->substream = substream;
-       spin_lock_init(&runtime->lock);
        init_waitqueue_head(&runtime->sleep);
        INIT_WORK(&runtime->event_work, snd_rawmidi_input_event_work);
        runtime->event = NULL;
@@ -203,20 +201,20 @@ static void __reset_runtime_ptrs(struct snd_rawmidi_runtime *runtime,
        runtime->avail = is_input ? 0 : runtime->buffer_size;
 }
 
-static void reset_runtime_ptrs(struct snd_rawmidi_runtime *runtime,
+static void reset_runtime_ptrs(struct snd_rawmidi_substream *substream,
                               bool is_input)
 {
        unsigned long flags;
 
-       spin_lock_irqsave(&runtime->lock, flags);
-       __reset_runtime_ptrs(runtime, is_input);
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
+       __reset_runtime_ptrs(substream->runtime, is_input);
+       spin_unlock_irqrestore(&substream->lock, flags);
 }
 
 int snd_rawmidi_drop_output(struct snd_rawmidi_substream *substream)
 {
        snd_rawmidi_output_trigger(substream, 0);
-       reset_runtime_ptrs(substream->runtime, false);
+       reset_runtime_ptrs(substream, false);
        return 0;
 }
 EXPORT_SYMBOL(snd_rawmidi_drop_output);
@@ -256,7 +254,7 @@ EXPORT_SYMBOL(snd_rawmidi_drain_output);
 int snd_rawmidi_drain_input(struct snd_rawmidi_substream *substream)
 {
        snd_rawmidi_input_trigger(substream, 0);
-       reset_runtime_ptrs(substream->runtime, true);
+       reset_runtime_ptrs(substream, true);
        return 0;
 }
 EXPORT_SYMBOL(snd_rawmidi_drain_input);
@@ -676,10 +674,11 @@ static int snd_rawmidi_info_select_user(struct snd_card *card,
        return 0;
 }
 
-static int resize_runtime_buffer(struct snd_rawmidi_runtime *runtime,
+static int resize_runtime_buffer(struct snd_rawmidi_substream *substream,
                                 struct snd_rawmidi_params *params,
                                 bool is_input)
 {
+       struct snd_rawmidi_runtime *runtime = substream->runtime;
        char *newbuf, *oldbuf;
        unsigned int framing = params->mode & SNDRV_RAWMIDI_MODE_FRAMING_MASK;
 
@@ -693,9 +692,9 @@ static int resize_runtime_buffer(struct snd_rawmidi_runtime *runtime,
                newbuf = kvzalloc(params->buffer_size, GFP_KERNEL);
                if (!newbuf)
                        return -ENOMEM;
-               spin_lock_irq(&runtime->lock);
+               spin_lock_irq(&substream->lock);
                if (runtime->buffer_ref) {
-                       spin_unlock_irq(&runtime->lock);
+                       spin_unlock_irq(&substream->lock);
                        kvfree(newbuf);
                        return -EBUSY;
                }
@@ -703,7 +702,7 @@ static int resize_runtime_buffer(struct snd_rawmidi_runtime *runtime,
                runtime->buffer = newbuf;
                runtime->buffer_size = params->buffer_size;
                __reset_runtime_ptrs(runtime, is_input);
-               spin_unlock_irq(&runtime->lock);
+               spin_unlock_irq(&substream->lock);
                kvfree(oldbuf);
        }
        runtime->avail_min = params->avail_min;
@@ -717,7 +716,7 @@ int snd_rawmidi_output_params(struct snd_rawmidi_substream *substream,
                return -EBUSY;
        snd_rawmidi_drain_output(substream);
        substream->active_sensing = !params->no_active_sensing;
-       return resize_runtime_buffer(substream->runtime, params, false);
+       return resize_runtime_buffer(substream, params, false);
 }
 EXPORT_SYMBOL(snd_rawmidi_output_params);
 
@@ -735,7 +734,7 @@ int snd_rawmidi_input_params(struct snd_rawmidi_substream *substream,
        if (framing > SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP)
                return -EINVAL;
        snd_rawmidi_drain_input(substream);
-       err = resize_runtime_buffer(substream->runtime, params, true);
+       err = resize_runtime_buffer(substream, params, true);
        if (err < 0)
                return err;
 
@@ -752,9 +751,9 @@ static int snd_rawmidi_output_status(struct snd_rawmidi_substream *substream,
 
        memset(status, 0, sizeof(*status));
        status->stream = SNDRV_RAWMIDI_STREAM_OUTPUT;
-       spin_lock_irq(&runtime->lock);
+       spin_lock_irq(&substream->lock);
        status->avail = runtime->avail;
-       spin_unlock_irq(&runtime->lock);
+       spin_unlock_irq(&substream->lock);
        return 0;
 }
 
@@ -765,11 +764,11 @@ static int snd_rawmidi_input_status(struct snd_rawmidi_substream *substream,
 
        memset(status, 0, sizeof(*status));
        status->stream = SNDRV_RAWMIDI_STREAM_INPUT;
-       spin_lock_irq(&runtime->lock);
+       spin_lock_irq(&substream->lock);
        status->avail = runtime->avail;
        status->xruns = runtime->xruns;
        runtime->xruns = 0;
-       spin_unlock_irq(&runtime->lock);
+       spin_unlock_irq(&substream->lock);
        return 0;
 }
 
@@ -1074,7 +1073,7 @@ int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,
                return -EINVAL;
        }
 
-       spin_lock_irqsave(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
        if (substream->framing == SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP) {
                result = receive_with_tstamp_framing(substream, buffer, count, &ts64);
        } else if (count == 1) {        /* special case, faster code */
@@ -1121,7 +1120,7 @@ int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,
                else if (__snd_rawmidi_ready(runtime))
                        wake_up(&runtime->sleep);
        }
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_unlock_irqrestore(&substream->lock, flags);
        return result;
 }
 EXPORT_SYMBOL(snd_rawmidi_receive);
@@ -1136,7 +1135,7 @@ static long snd_rawmidi_kernel_read1(struct snd_rawmidi_substream *substream,
        unsigned long appl_ptr;
        int err = 0;
 
-       spin_lock_irqsave(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
        snd_rawmidi_buffer_ref(runtime);
        while (count > 0 && runtime->avail) {
                count1 = runtime->buffer_size - runtime->appl_ptr;
@@ -1154,11 +1153,11 @@ static long snd_rawmidi_kernel_read1(struct snd_rawmidi_substream *substream,
                if (kernelbuf)
                        memcpy(kernelbuf + result, runtime->buffer + appl_ptr, count1);
                if (userbuf) {
-                       spin_unlock_irqrestore(&runtime->lock, flags);
+                       spin_unlock_irqrestore(&substream->lock, flags);
                        if (copy_to_user(userbuf + result,
                                         runtime->buffer + appl_ptr, count1))
                                err = -EFAULT;
-                       spin_lock_irqsave(&runtime->lock, flags);
+                       spin_lock_irqsave(&substream->lock, flags);
                        if (err)
                                goto out;
                }
@@ -1167,7 +1166,7 @@ static long snd_rawmidi_kernel_read1(struct snd_rawmidi_substream *substream,
        }
  out:
        snd_rawmidi_buffer_unref(runtime);
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_unlock_irqrestore(&substream->lock, flags);
        return result > 0 ? result : err;
 }
 
@@ -1196,31 +1195,31 @@ static ssize_t snd_rawmidi_read(struct file *file, char __user *buf, size_t coun
        snd_rawmidi_input_trigger(substream, 1);
        result = 0;
        while (count > 0) {
-               spin_lock_irq(&runtime->lock);
+               spin_lock_irq(&substream->lock);
                while (!__snd_rawmidi_ready(runtime)) {
                        wait_queue_entry_t wait;
 
                        if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
-                               spin_unlock_irq(&runtime->lock);
+                               spin_unlock_irq(&substream->lock);
                                return result > 0 ? result : -EAGAIN;
                        }
                        init_waitqueue_entry(&wait, current);
                        add_wait_queue(&runtime->sleep, &wait);
                        set_current_state(TASK_INTERRUPTIBLE);
-                       spin_unlock_irq(&runtime->lock);
+                       spin_unlock_irq(&substream->lock);
                        schedule();
                        remove_wait_queue(&runtime->sleep, &wait);
                        if (rfile->rmidi->card->shutdown)
                                return -ENODEV;
                        if (signal_pending(current))
                                return result > 0 ? result : -ERESTARTSYS;
-                       spin_lock_irq(&runtime->lock);
+                       spin_lock_irq(&substream->lock);
                        if (!runtime->avail) {
-                               spin_unlock_irq(&runtime->lock);
+                               spin_unlock_irq(&substream->lock);
                                return result > 0 ? result : -EIO;
                        }
                }
-               spin_unlock_irq(&runtime->lock);
+               spin_unlock_irq(&substream->lock);
                count1 = snd_rawmidi_kernel_read1(substream,
                                                  (unsigned char __user *)buf,
                                                  NULL/*kernelbuf*/,
@@ -1251,9 +1250,9 @@ int snd_rawmidi_transmit_empty(struct snd_rawmidi_substream *substream)
                          "snd_rawmidi_transmit_empty: output is not active!!!\n");
                return 1;
        }
-       spin_lock_irqsave(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
        result = runtime->avail >= runtime->buffer_size;
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_unlock_irqrestore(&substream->lock, flags);
        return result;
 }
 EXPORT_SYMBOL(snd_rawmidi_transmit_empty);
@@ -1322,13 +1321,12 @@ static int __snd_rawmidi_transmit_peek(struct snd_rawmidi_substream *substream,
 int snd_rawmidi_transmit_peek(struct snd_rawmidi_substream *substream,
                              unsigned char *buffer, int count)
 {
-       struct snd_rawmidi_runtime *runtime = substream->runtime;
        int result;
        unsigned long flags;
 
-       spin_lock_irqsave(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
        result = __snd_rawmidi_transmit_peek(substream, buffer, count);
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_unlock_irqrestore(&substream->lock, flags);
        return result;
 }
 EXPORT_SYMBOL(snd_rawmidi_transmit_peek);
@@ -1375,13 +1373,12 @@ static int __snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream,
  */
 int snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream, int count)
 {
-       struct snd_rawmidi_runtime *runtime = substream->runtime;
        int result;
        unsigned long flags;
 
-       spin_lock_irqsave(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
        result = __snd_rawmidi_transmit_ack(substream, count);
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_unlock_irqrestore(&substream->lock, flags);
        return result;
 }
 EXPORT_SYMBOL(snd_rawmidi_transmit_ack);
@@ -1399,11 +1396,10 @@ EXPORT_SYMBOL(snd_rawmidi_transmit_ack);
 int snd_rawmidi_transmit(struct snd_rawmidi_substream *substream,
                         unsigned char *buffer, int count)
 {
-       struct snd_rawmidi_runtime *runtime = substream->runtime;
        int result;
        unsigned long flags;
 
-       spin_lock_irqsave(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
        if (!substream->opened)
                result = -EBADFD;
        else {
@@ -1413,7 +1409,7 @@ int snd_rawmidi_transmit(struct snd_rawmidi_substream *substream,
                else
                        result = __snd_rawmidi_transmit_ack(substream, count);
        }
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_unlock_irqrestore(&substream->lock, flags);
        return result;
 }
 EXPORT_SYMBOL(snd_rawmidi_transmit);
@@ -1430,12 +1426,12 @@ int snd_rawmidi_proceed(struct snd_rawmidi_substream *substream)
        unsigned long flags;
        int count = 0;
 
-       spin_lock_irqsave(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
        if (runtime->avail < runtime->buffer_size) {
                count = runtime->buffer_size - runtime->avail;
                __snd_rawmidi_transmit_ack(substream, count);
        }
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_unlock_irqrestore(&substream->lock, flags);
        return count;
 }
 EXPORT_SYMBOL(snd_rawmidi_proceed);
@@ -1456,10 +1452,10 @@ static long snd_rawmidi_kernel_write1(struct snd_rawmidi_substream *substream,
                return -EINVAL;
 
        result = 0;
-       spin_lock_irqsave(&runtime->lock, flags);
+       spin_lock_irqsave(&substream->lock, flags);
        if (substream->append) {
                if ((long)runtime->avail < count) {
-                       spin_unlock_irqrestore(&runtime->lock, flags);
+                       spin_unlock_irqrestore(&substream->lock, flags);
                        return -EAGAIN;
                }
        }
@@ -1481,14 +1477,14 @@ static long snd_rawmidi_kernel_write1(struct snd_rawmidi_substream *substream,
                        memcpy(runtime->buffer + appl_ptr,
                               kernelbuf + result, count1);
                else if (userbuf) {
-                       spin_unlock_irqrestore(&runtime->lock, flags);
+                       spin_unlock_irqrestore(&substream->lock, flags);
                        if (copy_from_user(runtime->buffer + appl_ptr,
                                           userbuf + result, count1)) {
-                               spin_lock_irqsave(&runtime->lock, flags);
+                               spin_lock_irqsave(&substream->lock, flags);
                                result = result > 0 ? result : -EFAULT;
                                goto __end;
                        }
-                       spin_lock_irqsave(&runtime->lock, flags);
+                       spin_lock_irqsave(&substream->lock, flags);
                }
                result += count1;
                count -= count1;
@@ -1496,7 +1492,7 @@ static long snd_rawmidi_kernel_write1(struct snd_rawmidi_substream *substream,
       __end:
        count1 = runtime->avail < runtime->buffer_size;
        snd_rawmidi_buffer_unref(runtime);
-       spin_unlock_irqrestore(&runtime->lock, flags);
+       spin_unlock_irqrestore(&substream->lock, flags);
        if (count1)
                snd_rawmidi_output_trigger(substream, 1);
        return result;
@@ -1526,31 +1522,31 @@ static ssize_t snd_rawmidi_write(struct file *file, const char __user *buf,
                return -EIO;
        result = 0;
        while (count > 0) {
-               spin_lock_irq(&runtime->lock);
+               spin_lock_irq(&substream->lock);
                while (!snd_rawmidi_ready_append(substream, count)) {
                        wait_queue_entry_t wait;
 
                        if (file->f_flags & O_NONBLOCK) {
-                               spin_unlock_irq(&runtime->lock);
+                               spin_unlock_irq(&substream->lock);
                                return result > 0 ? result : -EAGAIN;
                        }
                        init_waitqueue_entry(&wait, current);
                        add_wait_queue(&runtime->sleep, &wait);
                        set_current_state(TASK_INTERRUPTIBLE);
-                       spin_unlock_irq(&runtime->lock);
+                       spin_unlock_irq(&substream->lock);
                        timeout = schedule_timeout(30 * HZ);
                        remove_wait_queue(&runtime->sleep, &wait);
                        if (rfile->rmidi->card->shutdown)
                                return -ENODEV;
                        if (signal_pending(current))
                                return result > 0 ? result : -ERESTARTSYS;
-                       spin_lock_irq(&runtime->lock);
+                       spin_lock_irq(&substream->lock);
                        if (!runtime->avail && !timeout) {
-                               spin_unlock_irq(&runtime->lock);
+                               spin_unlock_irq(&substream->lock);
                                return result > 0 ? result : -EIO;
                        }
                }
-               spin_unlock_irq(&runtime->lock);
+               spin_unlock_irq(&substream->lock);
                count1 = snd_rawmidi_kernel_write1(substream, buf, NULL, count);
                if (count1 < 0)
                        return result > 0 ? result : count1;
@@ -1561,7 +1557,7 @@ static ssize_t snd_rawmidi_write(struct file *file, const char __user *buf,
                count -= count1;
        }
        if (file->f_flags & O_DSYNC) {
-               spin_lock_irq(&runtime->lock);
+               spin_lock_irq(&substream->lock);
                while (runtime->avail != runtime->buffer_size) {
                        wait_queue_entry_t wait;
                        unsigned int last_avail = runtime->avail;
@@ -1569,16 +1565,16 @@ static ssize_t snd_rawmidi_write(struct file *file, const char __user *buf,
                        init_waitqueue_entry(&wait, current);
                        add_wait_queue(&runtime->sleep, &wait);
                        set_current_state(TASK_INTERRUPTIBLE);
-                       spin_unlock_irq(&runtime->lock);
+                       spin_unlock_irq(&substream->lock);
                        timeout = schedule_timeout(30 * HZ);
                        remove_wait_queue(&runtime->sleep, &wait);
                        if (signal_pending(current))
                                return result > 0 ? result : -ERESTARTSYS;
                        if (runtime->avail == last_avail && !timeout)
                                return result > 0 ? result : -EIO;
-                       spin_lock_irq(&runtime->lock);
+                       spin_lock_irq(&substream->lock);
                }
-               spin_unlock_irq(&runtime->lock);
+               spin_unlock_irq(&substream->lock);
        }
        return result;
 }
@@ -1649,10 +1645,10 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
                                    "  Owner PID    : %d\n",
                                    pid_vnr(substream->pid));
                                runtime = substream->runtime;
-                               spin_lock_irq(&runtime->lock);
+                               spin_lock_irq(&substream->lock);
                                buffer_size = runtime->buffer_size;
                                avail = runtime->avail;
-                               spin_unlock_irq(&runtime->lock);
+                               spin_unlock_irq(&substream->lock);
                                snd_iprintf(buffer,
                                    "  Mode         : %s\n"
                                    "  Buffer size  : %lu\n"
@@ -1676,11 +1672,11 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
                                            "  Owner PID    : %d\n",
                                            pid_vnr(substream->pid));
                                runtime = substream->runtime;
-                               spin_lock_irq(&runtime->lock);
+                               spin_lock_irq(&substream->lock);
                                buffer_size = runtime->buffer_size;
                                avail = runtime->avail;
                                xruns = runtime->xruns;
-                               spin_unlock_irq(&runtime->lock);
+                               spin_unlock_irq(&substream->lock);
                                snd_iprintf(buffer,
                                            "  Buffer size  : %lu\n"
                                            "  Avail        : %lu\n"
@@ -1732,6 +1728,7 @@ static int snd_rawmidi_alloc_substreams(struct snd_rawmidi *rmidi,
                substream->number = idx;
                substream->rmidi = rmidi;
                substream->pstr = stream;
+               spin_lock_init(&substream->lock);
                list_add_tail(&substream->list, &stream->substreams);
                stream->substream_count++;
        }