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Subject[tip:tracing/blktrace] blktrace: print human-readable act_mask
Commit-ID:  093419971e03362a00f499960557c119982ea09f
Gitweb: http://git.kernel.org/tip/093419971e03362a00f499960557c119982ea09f
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Tue, 24 Mar 2009 17:43:30 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 24 Mar 2009 13:09:00 +0100

blktrace: print human-readable act_mask

Impact: new feature, allow symbolic values in /debug/tracing/act_mask

Print stringified act_mask instead of hex value:

# cat act_mask
read,write,barrier,sync,queue,requeue,issue,complete,fs,pc,ahead,meta,
discard,drv_data
# echo "meta,write" > act_mask
# cat act_mask
write,meta
Also:
- make act_mask accept "ahead", "meta", "discard" and "drv_data"
- use strsep() instead of strchr() to parse user input
- return -EINVAL if a token is not found in the mask map
- fix a bug that 'value' is unsigned, so it can < 0
- propagate error value of blk_trace_mask2str() to userspace, but not
always return -ENXIO.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <49C8AB42.1000802@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
kernel/trace/blktrace.c | 103 +++++++++++++++++++++++++++++-----------------
1 files changed, 65 insertions(+), 38 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index f69f8bd..6fb274f 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1316,53 +1316,77 @@ struct attribute_group blk_trace_attr_group = {
.attrs = blk_trace_attrs,
};

-static int blk_str2act_mask(const char *str)
+static const struct {
+ int mask;
+ const char *str;
+} mask_maps[] = {
+ { BLK_TC_READ, "read" },
+ { BLK_TC_WRITE, "write" },
+ { BLK_TC_BARRIER, "barrier" },
+ { BLK_TC_SYNC, "sync" },
+ { BLK_TC_QUEUE, "queue" },
+ { BLK_TC_REQUEUE, "requeue" },
+ { BLK_TC_ISSUE, "issue" },
+ { BLK_TC_COMPLETE, "complete" },
+ { BLK_TC_FS, "fs" },
+ { BLK_TC_PC, "pc" },
+ { BLK_TC_AHEAD, "ahead" },
+ { BLK_TC_META, "meta" },
+ { BLK_TC_DISCARD, "discard" },
+ { BLK_TC_DRV_DATA, "drv_data" },
+};
+
+static int blk_trace_str2mask(const char *str)
{
+ int i;
int mask = 0;
- char *copy = kstrdup(str, GFP_KERNEL), *s;
+ char *s, *token;

- if (copy == NULL)
+ s = kstrdup(str, GFP_KERNEL);
+ if (s == NULL)
return -ENOMEM;
-
- s = strstrip(copy);
+ s = strstrip(s);

while (1) {
- char *sep = strchr(s, ',');
-
- if (sep != NULL)
- *sep = '\0';
-
- if (strcasecmp(s, "barrier") == 0)
- mask |= BLK_TC_BARRIER;
- else if (strcasecmp(s, "complete") == 0)
- mask |= BLK_TC_COMPLETE;
- else if (strcasecmp(s, "fs") == 0)
- mask |= BLK_TC_FS;
- else if (strcasecmp(s, "issue") == 0)
- mask |= BLK_TC_ISSUE;
- else if (strcasecmp(s, "pc") == 0)
- mask |= BLK_TC_PC;
- else if (strcasecmp(s, "queue") == 0)
- mask |= BLK_TC_QUEUE;
- else if (strcasecmp(s, "read") == 0)
- mask |= BLK_TC_READ;
- else if (strcasecmp(s, "requeue") == 0)
- mask |= BLK_TC_REQUEUE;
- else if (strcasecmp(s, "sync") == 0)
- mask |= BLK_TC_SYNC;
- else if (strcasecmp(s, "write") == 0)
- mask |= BLK_TC_WRITE;
-
- if (sep == NULL)
+ token = strsep(&s, ",");
+ if (token == NULL)
break;

- s = sep + 1;
+ if (*token == '\0')
+ continue;
+
+ for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
+ if (strcasecmp(token, mask_maps[i].str) == 0) {
+ mask |= mask_maps[i].mask;
+ break;
+ }
+ }
+ if (i == ARRAY_SIZE(mask_maps)) {
+ mask = -EINVAL;
+ break;
+ }
}
- kfree(copy);
+ kfree(s);

return mask;
}

+static ssize_t blk_trace_mask2str(char *buf, int mask)
+{
+ int i;
+ char *p = buf;
+
+ for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
+ if (mask & mask_maps[i].mask) {
+ p += sprintf(p, "%s%s",
+ (p == buf) ? "" : ",", mask_maps[i].str);
+ }
+ }
+ *p++ = '\n';
+
+ return p - buf;
+}
+
static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
{
if (bdev->bd_disk == NULL)
@@ -1399,7 +1423,7 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
if (q->blk_trace == NULL)
ret = sprintf(buf, "disabled\n");
else if (attr == &dev_attr_act_mask)
- ret = sprintf(buf, "%#x\n", q->blk_trace->act_mask);
+ ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
else if (attr == &dev_attr_pid)
ret = sprintf(buf, "%u\n", q->blk_trace->pid);
else if (attr == &dev_attr_start_lba)
@@ -1424,7 +1448,7 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
struct request_queue *q;
struct hd_struct *p;
u64 value;
- ssize_t ret = -ENXIO;
+ ssize_t ret = -EINVAL;

if (count == 0)
goto out;
@@ -1432,13 +1456,16 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
if (attr == &dev_attr_act_mask) {
if (sscanf(buf, "%llx", &value) != 1) {
/* Assume it is a list of trace category names */
- value = blk_str2act_mask(buf);
- if (value < 0)
+ ret = blk_trace_str2mask(buf);
+ if (ret < 0)
goto out;
+ value = ret;
}
} else if (sscanf(buf, "%llu", &value) != 1)
goto out;

+ ret = -ENXIO;
+
lock_kernel();
p = dev_to_part(dev);
bdev = bdget(part_devt(p));

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