Merge branch 'poll' into staging/for_v3.4

* poll: (5970 commits)
  poll: add poll_requested_events() and poll_does_not_wait() functions
  crc32: select an algorithm via Kconfig
  crc32: add self-test code for crc32c
  crypto: crc32c should use library implementation
  crc32: bolt on crc32c
  crc32: add note about this patchset to crc32.c
  crc32: optimize loop counter for x86
  crc32: add slice-by-8 algorithm to existing code
  crc32: make CRC_*_BITS definition correspond to actual bit counts
  crc32: fix mixing of endian-specific types
  crc32: miscellaneous cleanups
  crc32: simplify unit test code
  crc32: move long comment about crc32 fundamentals to Documentation/
  crc32: remove two instances of trailing whitespaces
  checkpatch: check for quoted strings broken across lines
  checkpatch: whitespace - add/remove blank lines
  checkpatch: warn on use of yield()
  checkpatch: add --strict tests for braces, comments and casts
  checkpatch: add [] to type extensions
  checkpatch: high precedence operators do not require additional parentheses in #defines
  ...

1 files changed, 60 insertions, 0 deletions

diff --git a/tools/perf/util/sysfs.c b/tools/perf/util/sysfs.c
new file mode 100644
index 000000000000..48c6902e749f
--- /dev/null
+++ b/tools/perf/util/sysfs.c
@@ -0,0 +1,60 @@
+
+#include "util.h"
+#include "sysfs.h"
+
+static const char * const sysfs_known_mountpoints[] = {
+	"/sys",
+	0,
+};
+
+static int sysfs_found;
+char sysfs_mountpoint[PATH_MAX];
+
+static int sysfs_valid_mountpoint(const char *sysfs)
+{
+	struct statfs st_fs;
+
+	if (statfs(sysfs, &st_fs) < 0)
+		return -ENOENT;
+	else if (st_fs.f_type != (long) SYSFS_MAGIC)
+		return -ENOENT;
+
+	return 0;
+}
+
+const char *sysfs_find_mountpoint(void)
+{
+	const char * const *ptr;
+	char type[100];
+	FILE *fp;
+
+	if (sysfs_found)
+		return (const char *) sysfs_mountpoint;
+
+	ptr = sysfs_known_mountpoints;
+	while (*ptr) {
+		if (sysfs_valid_mountpoint(*ptr) == 0) {
+			sysfs_found = 1;
+			strcpy(sysfs_mountpoint, *ptr);
+			return sysfs_mountpoint;
+		}
+		ptr++;
+	}
+
+	/* give up and parse /proc/mounts */
+	fp = fopen("/proc/mounts", "r");
+	if (fp == NULL)
+		return NULL;
+
+	while (!sysfs_found &&
+	       fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
+		      sysfs_mountpoint, type) == 2) {
+
+		if (strcmp(type, "sysfs") == 0)
+			sysfs_found = 1;
+	}
+
+	fclose(fp);
+
+	return sysfs_found ? sysfs_mountpoint : NULL;
+}