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Subject[PATCH] dyndbg: fix usability bug by adding pr_errs for -EINVALs
Date
A recent usability grumble on LKML prompted a review of error
reporting when writing dyndbg queries. For each -EINVAL, this adds
pr_err()s to explain the error.

To: Jason Baron <jbaron@redhat.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
lib/dynamic_debug.c | 40 ++++++++++++++++++++++++++++++----------
1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 7ca29a0..dd477ab 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -222,8 +222,10 @@ static int ddebug_tokenize(char *buf, char *words[], int maxwords)
int quote = *buf++;
for (end = buf ; *end && *end != quote ; end++)
;
- if (!*end)
+ if (!*end) {
+ pr_err("unclosed quote: %s\n", buf);
return -EINVAL; /* unclosed quote */
+ }
} else {
for (end = buf ; *end && !isspace(*end) ; end++)
;
@@ -231,8 +233,10 @@ static int ddebug_tokenize(char *buf, char *words[], int maxwords)
}

/* `buf' is start of word, `end' is one past its end */
- if (nwords == maxwords)
+ if (nwords == maxwords) {
+ pr_err("too many words, legal max <=%d\n", maxwords);
return -EINVAL; /* ran out of words[] before bytes */
+ }
if (*end)
*end++ = '\0'; /* terminate the word */
words[nwords++] = buf;
@@ -264,7 +268,11 @@ static inline int parse_lineno(const char *str, unsigned int *val)
return 0;
}
*val = simple_strtoul(str, &end, 10);
- return end == NULL || end == str || *end != '\0' ? -EINVAL : 0;
+ if (end == NULL || end == str || *end != '\0') {
+ pr_err("illegal line-number: %s\n", str);
+ return -EINVAL;
+ }
+ return 0;
}

/*
@@ -344,8 +352,10 @@ static int ddebug_parse_query(char *words[], int nwords,
int rc;

/* check we have an even number of words */
- if (nwords % 2 != 0)
+ if (nwords % 2 != 0) {
+ pr_err("legal query spec is pairs of: spec value\n");
return -EINVAL;
+ }
memset(query, 0, sizeof(*query));

if (modname)
@@ -371,8 +381,10 @@ static int ddebug_parse_query(char *words[], int nwords,
}
if (last)
*last++ = '\0';
- if (parse_lineno(first, &query->first_lineno) < 0)
+ if (parse_lineno(first, &query->first_lineno) < 0) {
+ pr_err("line-number is <0\n");
return -EINVAL;
+ }
if (last) {
/* range <first>-<last> */
if (parse_lineno(last, &query->last_lineno)
@@ -413,6 +425,7 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
op = *str++;
break;
default:
+ pr_err("bad flags-op, expecting [+-=], not %c\n", *str);
return -EINVAL;
}
vpr_info("op='%c'\n", op);
@@ -424,8 +437,10 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
break;
}
}
- if (i < 0)
+ if (i < 0) {
+ pr_err("unknown flag: %c\n", *str);
return -EINVAL;
+ }
}
vpr_info("flags=0x%x\n", flags);

@@ -457,13 +472,18 @@ static int ddebug_exec_query(char *query_string, const char *modname)
char *words[MAXWORDS];

nwords = ddebug_tokenize(query_string, words, MAXWORDS);
- if (nwords <= 0)
+ if (nwords <= 0) {
+ pr_err("tokenize failed\n");
return -EINVAL;
- if (ddebug_parse_query(words, nwords-1, &query, modname))
+ }
+ if (ddebug_parse_query(words, nwords-1, &query, modname)) {
+ pr_err("query spec parse failed\n");
return -EINVAL;
- if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
+ }
+ if (ddebug_parse_flags(words[nwords-1], &flags, &mask)) {
+ pr_err("flags parse failed\n");
return -EINVAL;
-
+ }
/* actually go and implement the change */
nfound = ddebug_change(&query, flags, mask);
vpr_info_dq((&query), (nfound) ? "applied" : "no-match");
--
1.7.10.1.487.ga3935e6


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