[PATCH 60/61] Dynamic debug: allow simple quoting of words

Greg Kroah-Hartman
2009-03-25T00:51:40Z

From: Greg Banks <gnb@melbourne.sgi.com>

Allow simple quoting of words in the dynamic debug control language.

This allows more natural specification when using the control language
to match against printk formats, e.g

#echo -n 'format "Setting node for non-present cpu" +p' >
/mnt/debugfs/dynamic_debug/control

instead of

#echo -n 'format Setting\040node\040for\040non-present\040cpu +p' >
/mnt/debugfs/dynamic_debug/control

Adjust the dynamic debug documention to describe that and provide a
new example. Adjust the existing examples in the documentation to
reflect the current whitespace escaping behaviour when reading the
control file. Fix some minor documentation trailing whitespace.

Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>
Acked-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
Documentation/dynamic-debug-howto.txt | 20 +++++++++----
lib/dynamic_debug.c | 53 ++++++++++++++++++++------------
2 files changed, 47 insertions(+), 26 deletions(-)

diff --git a/Documentation/dynamic-debug-howto.txt b/Documentation/dynamic-debug-howto.txt
index 6839482..674c566 100644
--- a/Documentation/dynamic-debug-howto.txt
+++ b/Documentation/dynamic-debug-howto.txt
@@ -49,10 +49,10 @@ via:

nullarbor:~ # cat <debugfs>/dynamic_debug/control
# filename:lineno [module]function flags format
-/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:323 [svcxprt_rdma]svc_rdma_cleanup - "SVCRDMA\040Module\040Removed,\040deregister\040RPC\040RDMA\040transport\012"
-/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:341 [svcxprt_rdma]svc_rdma_init - "\011max_inline\040\040\040\040\040\040\040:\040%d\012"
-/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:340 [svcxprt_rdma]svc_rdma_init - "\011sq_depth\040\040\040\040\040\040\040\040\040:\040%d\012"
-/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:338 [svcxprt_rdma]svc_rdma_init - "\011max_requests\040\040\040\040\040:\040%d\012"
+/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:323 [svcxprt_rdma]svc_rdma_cleanup - "SVCRDMA Module Removed, deregister RPC RDMA transport\012"
+/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:341 [svcxprt_rdma]svc_rdma_init - "\011max_inline : %d\012"
+/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:340 [svcxprt_rdma]svc_rdma_init - "\011sq_depth : %d\012"
+/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svc_rdma.c:338 [svcxprt_rdma]svc_rdma_init - "\011max_requests : %d\012"
...

@@ -72,7 +72,7 @@ you can view all the debug statement callsites with any non-default flags:

nullarbor:~ # awk '$3 != "-"' <debugfs>/dynamic_debug/control
# filename:lineno [module]function flags format
-/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svcsock.c:1603 [sunrpc]svc_send p "svc_process:\040st_sendto\040returned\040%d\012"
+/usr/src/packages/BUILD/sgi-enhancednfs-1.4/default/net/sunrpc/svcsock.c:1603 [sunrpc]svc_send p "svc_process: st_sendto returned %d\012"

Command Language Reference
@@ -166,11 +166,15 @@ format
entire format, only some part. Whitespace and other
special characters can be escaped using C octal character
escape \ooo notation, e.g. the space character is \040.
+ Alternatively, the string can be enclosed in double quote
+ characters (") or single quote characters (').
Examples:

format svcrdma: // many of the NFS/RDMA server dprintks
format readahead // some dprintks in the readahead cache
- format nfsd:\040SETATTR // how to match a format with whitespace
+ format nfsd:\040SETATTR // one way to match a format with whitespace
+ format "nfsd: SETATTR" // a neater way to match a format with whitespace
+ format 'nfsd: SETATTR' // yet another way to match a format with whitespace

line
The given line number or range of line numbers is compared
@@ -230,3 +234,7 @@ nullarbor:~ # echo -n 'func svc_process +p' >
// disable all 12 messages in the function svc_process()
nullarbor:~ # echo -n 'func svc_process -p' >
<debugfs>/dynamic_debug/control
+
+// enable messages for NFS calls READ, READLINK, READDIR and READDIR+.
+nullarbor:~ # echo -n 'format "nfsd: READ" +p' >
+ <debugfs>/dynamic_debug/control
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 9e123ae..833139c 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -196,32 +196,45 @@ static void ddebug_change(const struct ddebug_query *query,
}

/*
- * Wrapper around strsep() to collapse the multiple empty tokens
- * that it returns when fed sequences of separator characters.
- * Now, if we had strtok_r()...
- */
-static inline char *nearly_strtok_r(char **p, const char *sep)
-{
- char *r;
-
- while ((r = strsep(p, sep)) != NULL && *r == '\0')
- ;
- return r;
-}
-
-/*
* Split the buffer `buf' into space-separated words.
- * Return the number of such words or <0 on error.
+ * Handles simple " and ' quoting, i.e. without nested,
+ * embedded or escaped \". Return the number of words
+ * or <0 on error.
*/
static int ddebug_tokenize(char *buf, char *words[], int maxwords)
{
int nwords = 0;

- while (nwords < maxwords &&
- (words[nwords] = nearly_strtok_r(&buf, " \t\r\n")) != NULL)
- nwords++;
- if (buf)
- return -EINVAL; /* ran out of words[] before bytes */
+ while (*buf) {
+ char *end;
+
+ /* Skip leading whitespace */
+ while (*buf && isspace(*buf))
+ buf++;
+ if (!*buf)
+ break; /* oh, it was trailing whitespace */
+
+ /* Run `end' over a word, either whitespace separated or quoted */
+ if (*buf == '"' || *buf == '\'') {
+ int quote = *buf++;
+ for (end = buf ; *end && *end != quote ; end++)
+ ;
+ if (!*end)
+ return -EINVAL; /* unclosed quote */
+ } else {
+ for (end = buf ; *end && !isspace(*end) ; end++)
+ ;
+ BUG_ON(end == buf);
+ }
+ /* Here `buf' is the start of the word, `end' is one past the end */
+
+ if (nwords == maxwords)
+ return -EINVAL; /* ran out of words[] before bytes */
+ if (*end)
+ *end++ = '\0'; /* terminate the word */
+ words[nwords++] = buf;
+ buf = end;
+ }

if (verbose) {
int i;
--
1.6.2