1 files changed, 71 insertions, 131 deletions

diff --git a/kernel/relay.c b/kernel/relay.c
index d797502140b9..9988f5cc2d46 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -214,7 +214,7 @@ static void relay_destroy_buf(struct rchan_buf *buf)
 			__free_page(buf->page_array[i]);
 		relay_free_page_array(buf->page_array);
 	}
-	chan->buf[buf->cpu] = NULL;
+	*per_cpu_ptr(chan->buf, buf->cpu) = NULL;
 	kfree(buf->padding);
 	kfree(buf);
 	kref_put(&chan->kref, relay_destroy_channel);
@@ -382,20 +382,21 @@ static void __relay_reset(struct rchan_buf *buf, unsigned int init)
  */
 void relay_reset(struct rchan *chan)
 {
+	struct rchan_buf *buf;
 	unsigned int i;
 
 	if (!chan)
 		return;
 
-	if (chan->is_global && chan->buf[0]) {
-		__relay_reset(chan->buf[0], 0);
+	if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) {
+		__relay_reset(buf, 0);
 		return;
 	}
 
 	mutex_lock(&relay_channels_mutex);
 	for_each_possible_cpu(i)
-		if (chan->buf[i])
-			__relay_reset(chan->buf[i], 0);
+		if ((buf = *per_cpu_ptr(chan->buf, i)))
+			__relay_reset(buf, 0);
 	mutex_unlock(&relay_channels_mutex);
 }
 EXPORT_SYMBOL_GPL(relay_reset);
@@ -440,7 +441,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
 	struct dentry *dentry;
 
  	if (chan->is_global)
-		return chan->buf[0];
+		return *per_cpu_ptr(chan->buf, 0);
 
 	buf = relay_create_buf(chan);
 	if (!buf)
@@ -464,7 +465,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
  	__relay_reset(buf, 1);
 
  	if(chan->is_global) {
- 		chan->buf[0] = buf;
+		*per_cpu_ptr(chan->buf, 0) = buf;
  		buf->cpu = 0;
   	}
 
@@ -512,46 +513,25 @@ static void setup_callbacks(struct rchan *chan,
 	chan->cb = cb;
 }
 
-/**
- * 	relay_hotcpu_callback - CPU hotplug callback
- * 	@nb: notifier block
- * 	@action: hotplug action to take
- * 	@hcpu: CPU number
- *
- * 	Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
- */
-static int relay_hotcpu_callback(struct notifier_block *nb,
-				unsigned long action,
-				void *hcpu)
+int relay_prepare_cpu(unsigned int cpu)
 {
-	unsigned int hotcpu = (unsigned long)hcpu;
 	struct rchan *chan;
+	struct rchan_buf *buf;
 
-	switch(action) {
-	case CPU_UP_PREPARE:
-	case CPU_UP_PREPARE_FROZEN:
-		mutex_lock(&relay_channels_mutex);
-		list_for_each_entry(chan, &relay_channels, list) {
-			if (chan->buf[hotcpu])
-				continue;
-			chan->buf[hotcpu] = relay_open_buf(chan, hotcpu);
-			if(!chan->buf[hotcpu]) {
-				printk(KERN_ERR
-					"relay_hotcpu_callback: cpu %d buffer "
-					"creation failed\n", hotcpu);
-				mutex_unlock(&relay_channels_mutex);
-				return notifier_from_errno(-ENOMEM);
-			}
+	mutex_lock(&relay_channels_mutex);
+	list_for_each_entry(chan, &relay_channels, list) {
+		if ((buf = *per_cpu_ptr(chan->buf, cpu)))
+			continue;
+		buf = relay_open_buf(chan, cpu);
+		if (!buf) {
+			pr_err("relay: cpu %d buffer creation failed\n", cpu);
+			mutex_unlock(&relay_channels_mutex);
+			return -ENOMEM;
 		}
-		mutex_unlock(&relay_channels_mutex);
-		break;
-	case CPU_DEAD:
-	case CPU_DEAD_FROZEN:
-		/* No need to flush the cpu : will be flushed upon
-		 * final relay_flush() call. */
-		break;
+		*per_cpu_ptr(chan->buf, cpu) = buf;
 	}
-	return NOTIFY_OK;
+	mutex_unlock(&relay_channels_mutex);
+	return 0;
 }
 
 /**
@@ -583,6 +563,7 @@ struct rchan *relay_open(const char *base_filename,
 {
 	unsigned int i;
 	struct rchan *chan;
+	struct rchan_buf *buf;
 
 	if (!(subbuf_size && n_subbufs))
 		return NULL;
@@ -593,6 +574,7 @@ struct rchan *relay_open(const char *base_filename,
 	if (!chan)
 		return NULL;
 
+	chan->buf = alloc_percpu(struct rchan_buf *);
 	chan->version = RELAYFS_CHANNEL_VERSION;
 	chan->n_subbufs = n_subbufs;
 	chan->subbuf_size = subbuf_size;
@@ -608,9 +590,10 @@ struct rchan *relay_open(const char *base_filename,
 
 	mutex_lock(&relay_channels_mutex);
 	for_each_online_cpu(i) {
-		chan->buf[i] = relay_open_buf(chan, i);
-		if (!chan->buf[i])
+		buf = relay_open_buf(chan, i);
+		if (!buf)
 			goto free_bufs;
+		*per_cpu_ptr(chan->buf, i) = buf;
 	}
 	list_add(&chan->list, &relay_channels);
 	mutex_unlock(&relay_channels_mutex);
@@ -619,8 +602,8 @@ struct rchan *relay_open(const char *base_filename,
 
 free_bufs:
 	for_each_possible_cpu(i) {
-		if (chan->buf[i])
-			relay_close_buf(chan->buf[i]);
+		if ((buf = *per_cpu_ptr(chan->buf, i)))
+			relay_close_buf(buf);
 	}
 
 	kref_put(&chan->kref, relay_destroy_channel);
@@ -666,6 +649,7 @@ int relay_late_setup_files(struct rchan *chan,
 	unsigned int i, curr_cpu;
 	unsigned long flags;
 	struct dentry *dentry;
+	struct rchan_buf *buf;
 	struct rchan_percpu_buf_dispatcher disp;
 
 	if (!chan || !base_filename)
@@ -684,10 +668,11 @@ int relay_late_setup_files(struct rchan *chan,
 
 	if (chan->is_global) {
 		err = -EINVAL;
-		if (!WARN_ON_ONCE(!chan->buf[0])) {
-			dentry = relay_create_buf_file(chan, chan->buf[0], 0);
+		buf = *per_cpu_ptr(chan->buf, 0);
+		if (!WARN_ON_ONCE(!buf)) {
+			dentry = relay_create_buf_file(chan, buf, 0);
 			if (dentry && !WARN_ON_ONCE(!chan->is_global)) {
-				relay_set_buf_dentry(chan->buf[0], dentry);
+				relay_set_buf_dentry(buf, dentry);
 				err = 0;
 			}
 		}
@@ -702,13 +687,14 @@ int relay_late_setup_files(struct rchan *chan,
 	 * on all currently online CPUs.
 	 */
 	for_each_online_cpu(i) {
-		if (unlikely(!chan->buf[i])) {
+		buf = *per_cpu_ptr(chan->buf, i);
+		if (unlikely(!buf)) {
 			WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n");
 			err = -EINVAL;
 			break;
 		}
 
-		dentry = relay_create_buf_file(chan, chan->buf[i], i);
+		dentry = relay_create_buf_file(chan, buf, i);
 		if (unlikely(!dentry)) {
 			err = -EINVAL;
 			break;
@@ -716,10 +702,10 @@ int relay_late_setup_files(struct rchan *chan,
 
 		if (curr_cpu == i) {
 			local_irq_save(flags);
-			relay_set_buf_dentry(chan->buf[i], dentry);
+			relay_set_buf_dentry(buf, dentry);
 			local_irq_restore(flags);
 		} else {
-			disp.buf = chan->buf[i];
+			disp.buf = buf;
 			disp.dentry = dentry;
 			smp_mb();
 			/* relay_channels_mutex must be held, so wait. */
@@ -822,11 +808,10 @@ void relay_subbufs_consumed(struct rchan *chan,
 	if (!chan)
 		return;
 
-	if (cpu >= NR_CPUS || !chan->buf[cpu] ||
-					subbufs_consumed > chan->n_subbufs)
+	buf = *per_cpu_ptr(chan->buf, cpu);
+	if (cpu >= NR_CPUS || !buf || subbufs_consumed > chan->n_subbufs)
 		return;
 
-	buf = chan->buf[cpu];
 	if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed)
 		buf->subbufs_consumed = buf->subbufs_produced;
 	else
@@ -842,18 +827,19 @@ EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
  */
 void relay_close(struct rchan *chan)
 {
+	struct rchan_buf *buf;
 	unsigned int i;
 
 	if (!chan)
 		return;
 
 	mutex_lock(&relay_channels_mutex);
-	if (chan->is_global && chan->buf[0])
-		relay_close_buf(chan->buf[0]);
+	if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0)))
+		relay_close_buf(buf);
 	else
 		for_each_possible_cpu(i)
-			if (chan->buf[i])
-				relay_close_buf(chan->buf[i]);
+			if ((buf = *per_cpu_ptr(chan->buf, i)))
+				relay_close_buf(buf);
 
 	if (chan->last_toobig)
 		printk(KERN_WARNING "relay: one or more items not logged "
@@ -874,20 +860,21 @@ EXPORT_SYMBOL_GPL(relay_close);
  */
 void relay_flush(struct rchan *chan)
 {
+	struct rchan_buf *buf;
 	unsigned int i;
 
 	if (!chan)
 		return;
 
-	if (chan->is_global && chan->buf[0]) {
-		relay_switch_subbuf(chan->buf[0], 0);
+	if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) {
+		relay_switch_subbuf(buf, 0);
 		return;
 	}
 
 	mutex_lock(&relay_channels_mutex);
 	for_each_possible_cpu(i)
-		if (chan->buf[i])
-			relay_switch_subbuf(chan->buf[i], 0);
+		if ((buf = *per_cpu_ptr(chan->buf, i)))
+			relay_switch_subbuf(buf, 0);
 	mutex_unlock(&relay_channels_mutex);
 }
 EXPORT_SYMBOL_GPL(relay_flush);
@@ -1121,51 +1108,23 @@ static size_t relay_file_read_end_pos(struct rchan_buf *buf,
 	return end_pos;
 }
 
-/*
- *	subbuf_read_actor - read up to one subbuf's worth of data
- */
-static int subbuf_read_actor(size_t read_start,
-			     struct rchan_buf *buf,
-			     size_t avail,
-			     read_descriptor_t *desc)
-{
-	void *from;
-	int ret = 0;
-
-	from = buf->start + read_start;
-	ret = avail;
-	if (copy_to_user(desc->arg.buf, from, avail)) {
-		desc->error = -EFAULT;
-		ret = 0;
-	}
-	desc->arg.data += ret;
-	desc->written += ret;
-	desc->count -= ret;
-
-	return ret;
-}
-
-typedef int (*subbuf_actor_t) (size_t read_start,
-			       struct rchan_buf *buf,
-			       size_t avail,
-			       read_descriptor_t *desc);
-
-/*
- *	relay_file_read_subbufs - read count bytes, bridging subbuf boundaries
- */
-static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos,
-					subbuf_actor_t subbuf_actor,
-					read_descriptor_t *desc)
+static ssize_t relay_file_read(struct file *filp,
+			       char __user *buffer,
+			       size_t count,
+			       loff_t *ppos)
 {
 	struct rchan_buf *buf = filp->private_data;
 	size_t read_start, avail;
+	size_t written = 0;
 	int ret;
 
-	if (!desc->count)
+	if (!count)
 		return 0;
 
 	inode_lock(file_inode(filp));
 	do {
+		void *from;
+
 		if (!relay_file_read_avail(buf, *ppos))
 			break;
 
@@ -1174,32 +1133,22 @@ static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos,
 		if (!avail)
 			break;
 
-		avail = min(desc->count, avail);
-		ret = subbuf_actor(read_start, buf, avail, desc);
-		if (desc->error < 0)
+		avail = min(count, avail);
+		from = buf->start + read_start;
+		ret = avail;
+		if (copy_to_user(buffer, from, avail))
 			break;
 
-		if (ret) {
-			relay_file_read_consume(buf, read_start, ret);
-			*ppos = relay_file_read_end_pos(buf, read_start, ret);
-		}
-	} while (desc->count && ret);
-	inode_unlock(file_inode(filp));
+		buffer += ret;
+		written += ret;
+		count -= ret;
 
-	return desc->written;
-}
+		relay_file_read_consume(buf, read_start, ret);
+		*ppos = relay_file_read_end_pos(buf, read_start, ret);
+	} while (count);
+	inode_unlock(file_inode(filp));
 
-static ssize_t relay_file_read(struct file *filp,
-			       char __user *buffer,
-			       size_t count,
-			       loff_t *ppos)
-{
-	read_descriptor_t desc;
-	desc.written = 0;
-	desc.count = count;
-	desc.arg.buf = buffer;
-	desc.error = 0;
-	return relay_file_read_subbufs(filp, ppos, subbuf_read_actor, &desc);
+	return written;
 }
 
 static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
@@ -1377,12 +1326,3 @@ const struct file_operations relay_file_operations = {
 	.splice_read	= relay_file_splice_read,
 };
 EXPORT_SYMBOL_GPL(relay_file_operations);
-
-static __init int relay_init(void)
-{
-
-	hotcpu_notifier(relay_hotcpu_callback, 0);
-	return 0;
-}
-
-early_initcall(relay_init);