[PATCH 21/25] dynamic_debug: shrink struct pending query to size actually needed

Jim Cromie
2011-07-25T21:45:10Z

Remove struct pending_query's fixed sized char arrays; function,
filename, module, format, and replace them with a 0-sized charbuf.
Before the struct is allocd, determine the size needed to store
the 4 strings into the charbuf. Then copy the strings off the stack,
and update the field ptrs in the embedded struct ddebug_query to point
into the charbuf. This change uses strcpy instead of strlcpy, since
we know that the charbuf is big enough to hold the 4 strings.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
lib/dynamic_debug.c | 37 ++++++++++++++++++++++---------------
1 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 8f56092..5ec8165 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -56,11 +56,8 @@ struct ddebug_query {
struct pending_query {
struct list_head link;
struct ddebug_query query;
- char filename[100];
- char module[30];
- char function[50];
- char format[200];
unsigned int flags, mask;
+ char buf[0];
};

struct ddebug_iter {
@@ -507,7 +504,8 @@ static int ddebug_save_pending(struct ddebug_query *query,
unsigned int flags, unsigned int mask)
{
struct pending_query *pq, *pqnext;
- char *qstr;
+ char *qstr, *bp;
+ size_t buflen;

list_for_each_entry_safe(pq, pqnext, &pending_queries, link) {
if (queries_match(query, &pq->query)) {
@@ -537,26 +535,33 @@ static int ddebug_save_pending(struct ddebug_query *query,
pr_debug("add to pending: %s\n", qstr);
kfree(qstr);

- pq = kzalloc(sizeof(struct pending_query), GFP_KERNEL);
+ buflen = (query->module ? strlen(query->module) : 0)
+ + (query->function ? strlen(query->function) : 0)
+ + (query->filename ? strlen(query->filename) : 0)
+ + (query->format ? strlen(query->format) : 0)
+ + 4; /* for \0's */
+
+ pq = kzalloc(sizeof(struct pending_query) + buflen, GFP_KERNEL);
if (pq == NULL)
return -ENOMEM;

/* copy non-null match-specs into allocd mem, update pointers */
+ bp = pq->buf;
if (query->module) {
- strlcpy(pq->module, query->module, sizeof(pq->module));
- pq->query.module = pq->module;
+ pq->query.module = strcpy(bp, query->module);
+ bp += strlen(bp) + 1;
}
if (query->function) {
- strlcpy(pq->function, query->function, sizeof(pq->function));
- pq->query.function = pq->function;
+ pq->query.function = strcpy(bp, query->function);
+ bp += strlen(bp) + 1;
}
if (query->filename) {
- strlcpy(pq->filename, query->filename, sizeof(pq->filename));
- pq->query.filename = pq->filename;
+ pq->query.filename = strcpy(bp, query->filename);
+ bp += strlen(bp) + 1;
}
if (query->format) {
- strlcpy(pq->format, query->format, sizeof(pq->format));
- pq->query.format = pq->format;
+ pq->query.format = strcpy(bp, query->format);
+ bp += strlen(bp) + 1;
}
pq->flags = flags;
pq->mask = mask;
@@ -564,7 +569,9 @@ static int ddebug_save_pending(struct ddebug_query *query,
list_add(&pq->link, &pending_queries);
pending_ct++;

- pr_debug("query saved as pending %d\n", pending_ct);
+ pr_debug("query saved as pending %d, in %d+%d bytes\n",
+ pending_ct, sizeof(struct pending_query), buflen);
+
return 0;
}

--
1.7.4.1