[ltt-dev] [PATCH] ltt-relay: remove percpu data, use direct pointer

[Lai Jiangshan]

struct ltt_channel_buf_struct is percpu data, we can not
access it directly.

And this percpu data use channel->kref too, it's not right.

Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
---
 include/linux/ltt-relay.h |    1
 ltt/ltt-relay.c           |  118 +++++++++++++++-------------------------------
 2 files changed, 40 insertions(+), 79 deletions(-)
diff --git a/include/linux/ltt-relay.h b/include/linux/ltt-relay.h
index ac3415a..b26eaea 100644
--- a/include/linux/ltt-relay.h
+++ b/include/linux/ltt-relay.h
@@ -43,6 +43,7 @@ struct buf_page {
  * Per-cpu relay channel buffer
  */
 struct rchan_buf {
+	void *chan_private;		/* private data for this buf */
 	struct rchan *chan;		/* associated channel */
 	wait_queue_head_t read_wait;	/* reader wait queue */
 	struct timer_list timer; 	/* reader wake-up timer */
diff --git a/ltt/ltt-relay.c b/ltt/ltt-relay.c
index 7c544f4..d1ba449 100644
--- a/ltt/ltt-relay.c
+++ b/ltt/ltt-relay.c
@@ -176,10 +176,7 @@ static void ltt_buffer_begin_callback(struct rchan_buf *buf,
 static notrace void ltt_buffer_end_callback(struct rchan_buf *buf,
 		u64 tsc, unsigned int offset, unsigned int subbuf_idx)
 {
-	struct ltt_channel_struct *channel =
-		(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 	struct ltt_subbuffer_header *header =
 		(struct ltt_subbuffer_header *)
 			ltt_relay_offset_address(buf,
@@ -195,10 +192,7 @@ static notrace void ltt_buffer_end_callback(struct rchan_buf *buf,
 static notrace void ltt_deliver(struct rchan_buf *buf, unsigned int subbuf_idx,
 		void *subbuf)
 {
-	struct ltt_channel_struct *channel =
-		(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 
 	atomic_set(&ltt_buf->wakeup_readers, 1);
 }
@@ -259,10 +253,7 @@ static notrace void ltt_buf_unfull(struct rchan_buf *buf,
 		unsigned int subbuf_idx,
 		long offset)
 {
-	struct ltt_channel_struct *ltt_channel =
-		(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 
 	ltt_relay_wake_writers(ltt_buf);
 }
@@ -278,10 +269,7 @@ static notrace void ltt_buf_unfull(struct rchan_buf *buf,
 static int ltt_open(struct inode *inode, struct file *file)
 {
 	struct rchan_buf *buf = inode->i_private;
-	struct ltt_channel_struct *ltt_channel =
-		(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 
 	if (!atomic_long_add_unless(&ltt_buf->active_readers, 1, 1))
 		return -EBUSY;
@@ -298,10 +286,7 @@ static int ltt_open(struct inode *inode, struct file *file)
 static int ltt_release(struct inode *inode, struct file *file)
 {
 	struct rchan_buf *buf = inode->i_private;
-	struct ltt_channel_struct *ltt_channel =
-		(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 	int ret;
 
 	WARN_ON(atomic_long_read(&ltt_buf->active_readers) != 1);
@@ -323,10 +308,7 @@ static unsigned int ltt_poll(struct file *filp, poll_table *wait)
 	unsigned int mask = 0;
 	struct inode *inode = filp->f_dentry->d_inode;
 	struct rchan_buf *buf = inode->i_private;
-	struct ltt_channel_struct *ltt_channel =
-		(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 
 	if (filp->f_mode & FMODE_READ) {
 		poll_wait_set_exclusive(wait);
@@ -343,8 +325,7 @@ static unsigned int ltt_poll(struct file *filp, poll_table *wait)
 			else
 				return 0;
 		} else {
-			struct rchan *rchan =
-				ltt_channel->trans_channel_data;
+			struct rchan *rchan = buf->chan;
 			if (SUBBUF_TRUNC(local_read(&ltt_buf->offset),
 					buf->chan)
 			  - SUBBUF_TRUNC(atomic_long_read(
@@ -385,8 +366,7 @@ static int ltt_ioctl(struct inode *inode, struct file *filp,
 	struct rchan_buf *buf = inode->i_private;
 	struct ltt_channel_struct *ltt_channel =
 		(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 	u32 __user *argp = (u32 __user *)arg;
 
 	WARN_ON(atomic_long_read(&ltt_buf->active_readers) != 1);
@@ -518,10 +498,7 @@ static int subbuf_splice_actor(struct file *in,
 			       unsigned int flags)
 {
 	struct rchan_buf *buf = in->private_data;
-	struct ltt_channel_struct *ltt_channel =
-		(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 	unsigned int poff, subbuf_pages, nr_pages;
 	struct page *pages[PIPE_BUFFERS];
 	struct partial_page partial[PIPE_BUFFERS];
@@ -628,8 +605,7 @@ static void ltt_relay_print_subbuffer_errors(
 		long cons_off, unsigned int cpu)
 {
 	struct rchan *rchan = ltt_chan->trans_channel_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_chan->buf, cpu);
+	struct ltt_channel_buf_struct *ltt_buf = rchan->buf[cpu]->chan_private;
 	long cons_idx, commit_count, write_offset;
 
 	cons_idx = SUBBUF_INDEX(cons_off, rchan);
@@ -660,8 +636,7 @@ static void ltt_relay_print_errors(struct ltt_trace_struct *trace,
 		struct ltt_channel_struct *ltt_chan, int cpu)
 {
 	struct rchan *rchan = ltt_chan->trans_channel_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_chan->buf, cpu);
+	struct ltt_channel_buf_struct *ltt_buf = rchan->buf[cpu]->chan_private;
 	long cons_off;
 
 	for (cons_off = atomic_long_read(&ltt_buf->consumed);
@@ -676,8 +651,8 @@ static void ltt_relay_print_buffer_errors(struct ltt_channel_struct *ltt_chan,
 		unsigned int cpu)
 {
 	struct ltt_trace_struct *trace = ltt_chan->trace;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_chan->buf, cpu);
+	struct rchan *rchan = ltt_chan->trans_channel_data;
+	struct ltt_channel_buf_struct *ltt_buf = rchan->buf[cpu]->chan_private;
 
 	if (local_read(&ltt_buf->events_lost))
 		printk(KERN_ALERT
@@ -702,13 +677,6 @@ static void ltt_relay_remove_dirs(struct ltt_trace_struct *trace)
 	debugfs_remove(trace->dentry.trace_root);
 }
 
-static void ltt_relay_release_channel(struct kref *kref)
-{
-	struct ltt_channel_struct *ltt_chan = container_of(kref,
-			struct ltt_channel_struct, kref);
-	percpu_free(ltt_chan->buf);
-}
-
 /*
  * Create ltt buffer.
  */
@@ -716,18 +684,24 @@ static int ltt_relay_create_buffer(struct ltt_trace_struct *trace,
 		struct ltt_channel_struct *ltt_chan, struct rchan_buf *buf,
 		unsigned int cpu, unsigned int n_subbufs)
 {
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_chan->buf, cpu);
+	struct ltt_channel_buf_struct *ltt_buf;
 	unsigned int j;
 
+	ltt_buf = kzalloc_node(sizeof(*ltt_buf), GFP_KERNEL, cpu_to_node(cpu));
+	if (!ltt_buf)
+		return -ENOMEM;
+
 	ltt_buf->commit_count =
 		kzalloc_node(sizeof(ltt_buf->commit_count) * n_subbufs,
 			GFP_KERNEL, cpu_to_node(cpu));
-	if (!ltt_buf->commit_count)
+	if (!ltt_buf->commit_count) {
+		kfree(ltt_buf);
 		return -ENOMEM;
+	}
+	buf->chan_private = ltt_buf;
+
 	kref_get(&trace->kref);
 	kref_get(&trace->ltt_transport_kref);
-	kref_get(&ltt_chan->kref);
 	local_set(&ltt_buf->offset, ltt_subbuffer_header_size());
 	atomic_long_set(&ltt_buf->consumed, 0);
 	atomic_long_set(&ltt_buf->active_readers, 0);
@@ -752,15 +726,14 @@ static void ltt_relay_destroy_buffer(struct ltt_channel_struct *ltt_chan,
 		unsigned int cpu)
 {
 	struct ltt_trace_struct *trace = ltt_chan->trace;
-	struct ltt_channel_buf_struct *ltt_buf =
-		percpu_ptr(ltt_chan->buf, cpu);
+	struct rchan *rchan = ltt_chan->trans_channel_data;
+	struct ltt_channel_buf_struct *ltt_buf = rchan->buf[cpu]->chan_private;
 
 	kref_put(&ltt_chan->trace->ltt_transport_kref,
 		ltt_release_transport);
 	ltt_relay_print_buffer_errors(ltt_chan, cpu);
 	kfree(ltt_buf->commit_count);
-	ltt_buf->commit_count = NULL;
-	kref_put(&ltt_chan->kref, ltt_relay_release_channel);
+	kfree(ltt_buf);
 	kref_put(&trace->kref, ltt_release_trace);
 	wake_up_interruptible(&trace->kref_wq);
 }
@@ -790,18 +763,12 @@ static int ltt_relay_create_channel(const char *trace_name,
 	}
 	strncat(tmpname, "_", PATH_MAX-1-strlen(tmpname));
 
-	kref_init(&ltt_chan->kref);
-
 	ltt_chan->trace = trace;
 	ltt_chan->buffer_begin = ltt_buffer_begin_callback;
 	ltt_chan->buffer_end = ltt_buffer_end_callback;
 	ltt_chan->overwrite = overwrite;
 	ltt_chan->n_subbufs_order = get_count_order(n_subbufs);
 	ltt_chan->commit_count_mask = (~0UL >> ltt_chan->n_subbufs_order);
-	ltt_chan->buf = percpu_alloc_mask(sizeof(struct ltt_channel_buf_struct),
-					  GFP_KERNEL, cpu_possible_map);
-	if (!ltt_chan->buf)
-		goto ltt_percpu_alloc_error;
 	ltt_chan->trans_channel_data = ltt_relay_open(tmpname,
 			dir,
 			subbuf_size,
@@ -823,8 +790,6 @@ static int ltt_relay_create_channel(const char *trace_name,
 	goto end;
 
 relay_open_error:
-	percpu_free(ltt_chan->buf);
-ltt_percpu_alloc_error:
 	err = EPERM;
 end:
 	kfree(tmpname);
@@ -865,9 +830,12 @@ static void ltt_relay_async_wakeup_chan(struct ltt_channel_struct *ltt_channel)
 	struct rchan *rchan = ltt_channel->trans_channel_data;
 
 	for_each_possible_cpu(i) {
-		struct ltt_channel_buf_struct *ltt_buf =
-			percpu_ptr(ltt_channel->buf, i);
+		struct ltt_channel_buf_struct *ltt_buf;
 
+		if (!rchan->buf[i])
+			continue;
+
+		ltt_buf = rchan->buf[i]->chan_private;
 		if (atomic_read(&ltt_buf->wakeup_readers) == 1) {
 			atomic_set(&ltt_buf->wakeup_readers, 0);
 			wake_up_interruptible(&rchan->buf[i]->read_wait);
@@ -882,7 +850,7 @@ static void ltt_relay_finish_buffer(struct ltt_channel_struct *ltt_channel,
 
 	if (rchan->buf[cpu]) {
 		struct ltt_channel_buf_struct *ltt_buf =
-			percpu_ptr(ltt_channel->buf, cpu);
+				rchan->buf[cpu]->chan_private;
 		ltt_relay_buffer_flush(rchan->buf[cpu]);
 		ltt_relay_wake_writers(ltt_buf);
 	}
@@ -902,7 +870,6 @@ static void ltt_relay_remove_channel(struct ltt_channel_struct *channel)
 	struct rchan *rchan = channel->trans_channel_data;
 
 	ltt_relay_close(rchan);
-	kref_put(&channel->kref, ltt_relay_release_channel);
 }
 
 struct ltt_reserve_switch_offsets {
@@ -1299,10 +1266,8 @@ static notrace int ltt_relay_reserve_slot(struct ltt_trace_struct *trace,
 		unsigned int *rflags, int largest_align, int cpu)
 {
 	struct rchan *rchan = ltt_channel->trans_channel_data;
-	struct rchan_buf *buf = *transport_data =
-			rchan->buf[cpu];
-	struct ltt_channel_buf_struct *ltt_buf =
-			percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct rchan_buf *buf = *transport_data = rchan->buf[cpu];
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 	struct ltt_reserve_switch_offsets offsets;
 
 	offsets.reserve_commit_diff = 0;
@@ -1373,8 +1338,7 @@ static notrace void ltt_force_switch(struct rchan_buf *buf,
 {
 	struct ltt_channel_struct *ltt_channel =
 			(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-			percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 	struct rchan *rchan = ltt_channel->trans_channel_data;
 	struct ltt_reserve_switch_offsets offsets;
 	u64 tsc;
@@ -1435,10 +1399,7 @@ static notrace void ltt_force_switch(struct rchan_buf *buf,
 static inline void ltt_write_commit_counter(struct rchan_buf *buf,
 		long buf_offset, size_t slot_size)
 {
-	struct ltt_channel_struct *ltt_channel =
-		(struct ltt_channel_struct *)buf->chan->private_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-			percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 	struct ltt_subbuffer_header *header;
 	long offset, subbuf_idx, commit_count;
 	uint32_t lost_old, lost_new;
@@ -1488,8 +1449,7 @@ static notrace void ltt_relay_commit_slot(
 		void **transport_data, long buf_offset, size_t slot_size)
 {
 	struct rchan_buf *buf = *transport_data;
-	struct ltt_channel_buf_struct *ltt_buf =
-			percpu_ptr(ltt_channel->buf, buf->cpu);
+	struct ltt_channel_buf_struct *ltt_buf = buf->chan_private;
 	struct rchan *rchan = buf->chan;
 	long offset_end = buf_offset;
 	long endidx = SUBBUF_INDEX(offset_end - 1, rchan);
@@ -1532,7 +1492,7 @@ static int ltt_relay_user_blocking(struct ltt_trace_struct *trace,
 	rchan = channel->trans_channel_data;
 	cpu = smp_processor_id();
 	relay_buf = rchan->buf[cpu];
-	ltt_buf = percpu_ptr(channel->buf, cpu);
+	ltt_buf = relay_buf->chan_private;
 
 	/*
 	 * Check if data is too big for the channel : do not
@@ -1583,7 +1543,7 @@ static void ltt_relay_print_user_errors(struct ltt_trace_struct *trace,
 	channel = &trace->channels[chan_index];
 	rchan = channel->trans_channel_data;
 	relay_buf = rchan->buf[cpu];
-	ltt_buf = percpu_ptr(channel->buf, cpu);
+	ltt_buf = relay_buf->chan_private;
 
 	printk(KERN_ERR "Error in LTT usertrace : "
 	"buffer full : event lost in blocking "