3 files changed, 81 insertions, 56 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
index 010a51f59796..adb5abb9af5d 100644
--- a/arch/powerpc/platforms/cell/spufs/file.c
+++ b/arch/powerpc/platforms/cell/spufs/file.c
@@ -2426,38 +2426,48 @@ static inline int spufs_switch_log_avail(struct spu_context *ctx)
 static int spufs_switch_log_open(struct inode *inode, struct file *file)
 {
 	struct spu_context *ctx = SPUFS_I(inode)->i_ctx;
+	int rc;
+
+	rc = spu_acquire(ctx);
+	if (rc)
+		return rc;
 
-	/*
-	 * We (ab-)use the mapping_lock here because it serves the similar
-	 * purpose for synchronizing open/close elsewhere.  Maybe it should
-	 * be renamed eventually.
-	 */
-	mutex_lock(&ctx->mapping_lock);
 	if (ctx->switch_log) {
-		spin_lock(&ctx->switch_log->lock);
-		ctx->switch_log->head = 0;
-		ctx->switch_log->tail = 0;
-		spin_unlock(&ctx->switch_log->lock);
-	} else {
-		/*
-		 * We allocate the switch log data structures on first open.
-		 * They will never be free because we assume a context will
-		 * be traced until it goes away.
-		 */
-		ctx->switch_log = kzalloc(sizeof(struct switch_log) +
-			SWITCH_LOG_BUFSIZE * sizeof(struct switch_log_entry),
-			GFP_KERNEL);
-		if (!ctx->switch_log)
-			goto out;
-		spin_lock_init(&ctx->switch_log->lock);
-		init_waitqueue_head(&ctx->switch_log->wait);
+		rc = -EBUSY;
+		goto out;
 	}
-	mutex_unlock(&ctx->mapping_lock);
+
+	ctx->switch_log = kzalloc(sizeof(struct switch_log) +
+		SWITCH_LOG_BUFSIZE * sizeof(struct switch_log_entry),
+		GFP_KERNEL);
+
+	if (!ctx->switch_log) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	init_waitqueue_head(&ctx->switch_log->wait);
+	rc = 0;
+
+out:
+	spu_release(ctx);
+	return rc;
+}
+
+static int spufs_switch_log_release(struct inode *inode, struct file *file)
+{
+	struct spu_context *ctx = SPUFS_I(inode)->i_ctx;
+	int rc;
+
+	rc = spu_acquire(ctx);
+	if (rc)
+		return rc;
+
+	kfree(ctx->switch_log);
+	ctx->switch_log = NULL;
+	spu_release(ctx);
 
 	return 0;
- out:
-	mutex_unlock(&ctx->mapping_lock);
-	return -ENOMEM;
 }
 
 static int switch_log_sprint(struct spu_context *ctx, char *tbuf, int n)
@@ -2485,42 +2495,46 @@ static ssize_t spufs_switch_log_read(struct file *file, char __user *buf,
 	if (!buf || len < 0)
 		return -EINVAL;
 
+	error = spu_acquire(ctx);
+	if (error)
+		return error;
+
 	while (cnt < len) {
 		char tbuf[128];
 		int width;
 
 		if (file->f_flags & O_NONBLOCK) {
-			if (spufs_switch_log_used(ctx) <= 0)
-				return cnt ? cnt : -EAGAIN;
+			if (spufs_switch_log_used(ctx) == 0) {
+				error = -EAGAIN;
+				break;
+			}
 		} else {
-			/* Wait for data in buffer */
-			error = wait_event_interruptible(ctx->switch_log->wait,
+			/* spufs_wait will drop the mutex and re-acquire,
+			 * but since we're in read(), the file cannot be
+			 * _released (and so ctx->switch_log is stable).
+			 */
+			error = spufs_wait(ctx->switch_log->wait,
 					spufs_switch_log_used(ctx) > 0);
+
+			/* On error, spufs_wait returns without the
+			 * state mutex held */
 			if (error)
-				break;
+				return error;
 		}
 
-		spin_lock(&ctx->switch_log->lock);
-		if (ctx->switch_log->head == ctx->switch_log->tail) {
-			/* multiple readers race? */
-			spin_unlock(&ctx->switch_log->lock);
+		/* We may have had entries read from underneath us while we
+		 * dropped the mutex in spufs_wait, so re-check */
+		if (ctx->switch_log->head == ctx->switch_log->tail)
 			continue;
-		}
 
 		width = switch_log_sprint(ctx, tbuf, sizeof(tbuf));
-		if (width < len) {
+		if (width < len)
 			ctx->switch_log->tail =
 				(ctx->switch_log->tail + 1) %
 				 SWITCH_LOG_BUFSIZE;
-		}
-
-		spin_unlock(&ctx->switch_log->lock);
-
-		/*
-		 * If the record is greater than space available return
-		 * partial buffer (so far)
-		 */
-		if (width >= len)
+		else
+			/* If the record is greater than space available return
+			 * partial buffer (so far) */
 			break;
 
 		error = copy_to_user(buf + cnt, tbuf, width);
@@ -2529,6 +2543,8 @@ static ssize_t spufs_switch_log_read(struct file *file, char __user *buf,
 		cnt += width;
 	}
 
+	spu_release(ctx);
+
 	return cnt == 0 ? error : cnt;
 }
 
@@ -2537,29 +2553,41 @@ static unsigned int spufs_switch_log_poll(struct file *file, poll_table *wait)
 	struct inode *inode = file->f_path.dentry->d_inode;
 	struct spu_context *ctx = SPUFS_I(inode)->i_ctx;
 	unsigned int mask = 0;
+	int rc;
 
 	poll_wait(file, &ctx->switch_log->wait, wait);
 
+	rc = spu_acquire(ctx);
+	if (rc)
+		return rc;
+
 	if (spufs_switch_log_used(ctx) > 0)
 		mask |= POLLIN;
 
+	spu_release(ctx);
+
 	return mask;
 }
 
 static const struct file_operations spufs_switch_log_fops = {
-	.owner	= THIS_MODULE,
-	.open	= spufs_switch_log_open,
-	.read	= spufs_switch_log_read,
-	.poll	= spufs_switch_log_poll,
+	.owner		= THIS_MODULE,
+	.open		= spufs_switch_log_open,
+	.read		= spufs_switch_log_read,
+	.poll		= spufs_switch_log_poll,
+	.release	= spufs_switch_log_release,
 };
 
+/**
+ * Log a context switch event to a switch log reader.
+ *
+ * Must be called with ctx->state_mutex held.
+ */
 void spu_switch_log_notify(struct spu *spu, struct spu_context *ctx,
 		u32 type, u32 val)
 {
 	if (!ctx->switch_log)
 		return;
 
-	spin_lock(&ctx->switch_log->lock);
 	if (spufs_switch_log_avail(ctx) > 1) {
 		struct switch_log_entry *p;
 
@@ -2573,7 +2601,6 @@ void spu_switch_log_notify(struct spu *spu, struct spu_context *ctx,
 		ctx->switch_log->head =
 			(ctx->switch_log->head + 1) % SWITCH_LOG_BUFSIZE;
 	}
-	spin_unlock(&ctx->switch_log->lock);
 
 	wake_up(&ctx->switch_log->wait);
 }
diff --git a/arch/powerpc/platforms/cell/spufs/run.c b/arch/powerpc/platforms/cell/spufs/run.c
index c9bb7cfd3dca..c58bd36b0c5b 100644
--- a/arch/powerpc/platforms/cell/spufs/run.c
+++ b/arch/powerpc/platforms/cell/spufs/run.c
@@ -249,6 +249,7 @@ static int spu_run_fini(struct spu_context *ctx, u32 *npc,
 
 	spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
 	clear_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags);
+	spu_switch_log_notify(NULL, ctx, SWITCH_LOG_EXIT, *status);
 	spu_release(ctx);
 
 	if (signal_pending(current))
@@ -417,8 +418,6 @@ long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
 	ret = spu_run_fini(ctx, npc, &status);
 	spu_yield(ctx);
 
-	spu_switch_log_notify(NULL, ctx, SWITCH_LOG_EXIT, status);
-
 	if ((status & SPU_STATUS_STOPPED_BY_STOP) &&
 	    (((status >> SPU_STOP_STATUS_SHIFT) & 0x3f00) == 0x2100))
 		ctx->stats.libassist++;
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index 8ae8ef9dfc22..15c62d3ca129 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -65,7 +65,6 @@ enum {
 };
 
 struct switch_log {
-	spinlock_t		lock;
 	wait_queue_head_t	wait;
 	unsigned long		head;
 	unsigned long		tail;