Merge branch 'perf/core' into perf/uprobes

Merge in latest upstream (and the latest perf development tree),
to prepare for tooling changes, and also to pick up v3.4 MM
changes that the uprobes code needs to take care of.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 55 insertions, 23 deletions

diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c
index ffc2d043dd8e..ea69b6a77dac 100644
--- a/drivers/staging/android/logger.c
+++ b/drivers/staging/android/logger.c
@@ -60,7 +60,11 @@ struct logger_reader {
 };
 
 /* logger_offset - returns index 'n' into the log via (optimized) modulus */
-#define logger_offset(n)	((n) & (log->size - 1))
+size_t logger_offset(struct logger_log *log, size_t n)
+{
+	return n & (log->size-1);
+}
+
 
 /*
  * file_get_log - Given a file structure, return the associated log
@@ -89,20 +93,24 @@ static inline struct logger_log *file_get_log(struct file *file)
  * get_entry_len - Grabs the length of the payload of the next entry starting
  * from 'off'.
  *
+ * An entry length is 2 bytes (16 bits) in host endian order.
+ * In the log, the length does not include the size of the log entry structure.
+ * This function returns the size including the log entry structure.
+ *
  * Caller needs to hold log->mutex.
  */
 static __u32 get_entry_len(struct logger_log *log, size_t off)
 {
 	__u16 val;
 
-	switch (log->size - off) {
-	case 1:
-		memcpy(&val, log->buffer + off, 1);
-		memcpy(((char *) &val) + 1, log->buffer, 1);
-		break;
-	default:
-		memcpy(&val, log->buffer + off, 2);
-	}
+	/* copy 2 bytes from buffer, in memcpy order, */
+	/* handling possible wrap at end of buffer */
+
+	((__u8 *)&val)[0] = log->buffer[off];
+	if (likely(off+1 < log->size))
+		((__u8 *)&val)[1] = log->buffer[off+1];
+	else
+		((__u8 *)&val)[1] = log->buffer[0];
 
 	return sizeof(struct logger_entry) + val;
 }
@@ -137,7 +145,7 @@ static ssize_t do_read_log_to_user(struct logger_log *log,
 		if (copy_to_user(buf + len, log->buffer, count - len))
 			return -EFAULT;
 
-	reader->r_off = logger_offset(reader->r_off + count);
+	reader->r_off = logger_offset(log, reader->r_off + count);
 
 	return count;
 }
@@ -164,9 +172,10 @@ static ssize_t logger_read(struct file *file, char __user *buf,
 
 start:
 	while (1) {
+		mutex_lock(&log->mutex);
+
 		prepare_to_wait(&log->wq, &wait, TASK_INTERRUPTIBLE);
 
-		mutex_lock(&log->mutex);
 		ret = (log->w_off == reader->r_off);
 		mutex_unlock(&log->mutex);
 		if (!ret)
@@ -225,7 +234,7 @@ static size_t get_next_entry(struct logger_log *log, size_t off, size_t len)
 
 	do {
 		size_t nr = get_entry_len(log, off);
-		off = logger_offset(off + nr);
+		off = logger_offset(log, off + nr);
 		count += nr;
 	} while (count < len);
 
@@ -233,16 +242,28 @@ static size_t get_next_entry(struct logger_log *log, size_t off, size_t len)
 }
 
 /*
- * clock_interval - is a < c < b in mod-space? Put another way, does the line
- * from a to b cross c?
+ * is_between - is a < c < b, accounting for wrapping of a, b, and c
+ *    positions in the buffer
+ *
+ * That is, if a<b, check for c between a and b
+ * and if a>b, check for c outside (not between) a and b
+ *
+ * |------- a xxxxxxxx b --------|
+ *               c^
+ *
+ * |xxxxx b --------- a xxxxxxxxx|
+ *    c^
+ *  or                    c^
  */
-static inline int clock_interval(size_t a, size_t b, size_t c)
+static inline int is_between(size_t a, size_t b, size_t c)
 {
-	if (b < a) {
-		if (a < c || b >= c)
+	if (a < b) {
+		/* is c between a and b? */
+		if (a < c && c <= b)
 			return 1;
 	} else {
-		if (a < c && b >= c)
+		/* is c outside of b through a? */
+		if (c <= b || a < c)
 			return 1;
 	}
 
@@ -260,14 +281,14 @@ static inline int clock_interval(size_t a, size_t b, size_t c)
 static void fix_up_readers(struct logger_log *log, size_t len)
 {
 	size_t old = log->w_off;
-	size_t new = logger_offset(old + len);
+	size_t new = logger_offset(log, old + len);
 	struct logger_reader *reader;
 
-	if (clock_interval(old, new, log->head))
+	if (is_between(old, new, log->head))
 		log->head = get_next_entry(log, log->head, len);
 
 	list_for_each_entry(reader, &log->readers, list)
-		if (clock_interval(old, new, reader->r_off))
+		if (is_between(old, new, reader->r_off))
 			reader->r_off = get_next_entry(log, reader->r_off, len);
 }
 
@@ -286,7 +307,7 @@ static void do_write_log(struct logger_log *log, const void *buf, size_t count)
 	if (count != len)
 		memcpy(log->buffer, buf + len, count - len);
 
-	log->w_off = logger_offset(log->w_off + count);
+	log->w_off = logger_offset(log, log->w_off + count);
 
 }
 
@@ -309,9 +330,15 @@ static ssize_t do_write_log_from_user(struct logger_log *log,
 
 	if (count != len)
 		if (copy_from_user(log->buffer, buf + len, count - len))
+			/*
+			 * Note that by not updating w_off, this abandons the
+			 * portion of the new entry that *was* successfully
+			 * copied, just above.  This is intentional to avoid
+			 * message corruption from missing fragments.
+			 */
 			return -EFAULT;
 
-	log->w_off = logger_offset(log->w_off + count);
+	log->w_off = logger_offset(log, log->w_off + count);
 
 	return count;
 }
@@ -432,7 +459,12 @@ static int logger_release(struct inode *ignored, struct file *file)
 {
 	if (file->f_mode & FMODE_READ) {
 		struct logger_reader *reader = file->private_data;
+		struct logger_log *log = reader->log;
+
+		mutex_lock(&log->mutex);
 		list_del(&reader->list);
+		mutex_unlock(&log->mutex);
+
 		kfree(reader);
 	}