tracing: Add full state to trace_seq

The trace_seq buffer might fill up, and right now one needs to check the return value of each printf into the buffer to check for that. Instead, have the buffer keep track of whether it is full or not, and reject more input if it is full or would have overflowed with an input that wasn't added. Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

tracing: Add full state to trace_seq
The trace_seq buffer might fill up, and right now one needs to check the return value of each printf into the buffer to check for that. Instead, have the buffer keep track of whether it is full or not, and reject more input if it is full or would have overflowed with an input that wasn't added. Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Johannes Berg · Steven Rostedt
1 parent a63ce5b306
Showing 2 changed files with 52 additions and 11 deletions Side-by-side Diff
include/linux/trace_seq.h
kernel/trace/trace_output.c
@@ -14,6 +14,7 @@
 	unsigned char		buffer[PAGE_SIZE];
 	unsigned int		len;
 	unsigned int		readpos;
+	int			full;
 };
  
 static inline void
@@ -21,6 +22,7 @@
 {
 	s->len = 0;
 	s->readpos = 0;
+	s->full = 0;
 }
  
 /*
@@ -93,7 +93,7 @@
 	va_list ap;
 	int ret;
  
-	if (!len)
+	if (s->full || !len)
 		return 0;
  
 	va_start(ap, fmt);
  
@@ -101,8 +101,10 @@
 	va_end(ap);
  
 	/* If we can't write it all, don't bother writing anything */
-	if (ret >= len)
+	if (ret >= len) {
+		s->full = 1;
 		return 0;
+	}
  
 	s->len += ret;
  
  
  
@@ -127,14 +129,16 @@
 	int len = (PAGE_SIZE - 1) - s->len;
 	int ret;
  
-	if (!len)
+	if (s->full || !len)
 		return 0;
  
 	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
  
 	/* If we can't write it all, don't bother writing anything */
-	if (ret >= len)
+	if (ret >= len) {
+		s->full = 1;
 		return 0;
+	}
  
 	s->len += ret;
  
  
  
@@ -147,14 +151,16 @@
 	int len = (PAGE_SIZE - 1) - s->len;
 	int ret;
  
-	if (!len)
+	if (s->full || !len)
 		return 0;
  
 	ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
  
 	/* If we can't write it all, don't bother writing anything */
-	if (ret >= len)
+	if (ret >= len) {
+		s->full = 1;
 		return 0;
+	}
  
 	s->len += ret;
  
  
@@ -175,9 +181,14 @@
 {
 	int len = strlen(str);
  
-	if (len > ((PAGE_SIZE - 1) - s->len))
+	if (s->full)
 		return 0;
  
+	if (len > ((PAGE_SIZE - 1) - s->len)) {
+		s->full = 1;
+		return 0;
+	}
+
 	memcpy(s->buffer + s->len, str, len);
 	s->len += len;
  
  
@@ -186,9 +197,14 @@
  
 int trace_seq_putc(struct trace_seq *s, unsigned char c)
 {
-	if (s->len >= (PAGE_SIZE - 1))
+	if (s->full)
 		return 0;
  
+	if (s->len >= (PAGE_SIZE - 1)) {
+		s->full = 1;
+		return 0;
+	}
+
 	s->buffer[s->len++] = c;
  
 	return 1;
  
@@ -196,9 +212,14 @@
  
 int trace_seq_putmem(struct trace_seq *s, const void *mem, size_t len)
 {
-	if (len > ((PAGE_SIZE - 1) - s->len))
+	if (s->full)
 		return 0;
  
+	if (len > ((PAGE_SIZE - 1) - s->len)) {
+		s->full = 1;
+		return 0;
+	}
+
 	memcpy(s->buffer + s->len, mem, len);
 	s->len += len;
  
@@ -211,6 +232,9 @@
 	const unsigned char *data = mem;
 	int i, j;
  
+	if (s->full)
+		return 0;
+
 #ifdef __BIG_ENDIAN
 	for (i = 0, j = 0; i < len; i++) {
 #else
  
@@ -228,8 +252,13 @@
 {
 	void *ret;
  
-	if (len > ((PAGE_SIZE - 1) - s->len))
+	if (s->full)
+		return 0;
+
+	if (len > ((PAGE_SIZE - 1) - s->len)) {
+		s->full = 1;
 		return NULL;
+	}
  
 	ret = s->buffer + s->len;
 	s->len += len;
  
@@ -241,8 +270,14 @@
 {
 	unsigned char *p;
  
-	if (s->len >= (PAGE_SIZE - 1))
+	if (s->full)
 		return 0;
+
+	if (s->len >= (PAGE_SIZE - 1)) {
+		s->full = 1;
+		return 0;
+	}
+
 	p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
 	if (!IS_ERR(p)) {
 		p = mangle_path(s->buffer + s->len, p, "\n");
@@ -255,6 +290,7 @@
 		return 1;
 	}
  
+	s->full = 1;
 	return 0;
 }
  
@@ -380,6 +416,9 @@
 	struct file *file = NULL;
 	unsigned long vmstart = 0;
 	int ret = 1;
+
+	if (s->full)
+		return 0;
  
 	if (mm) {
 		const struct vm_area_struct *vma;
...	...	@@ -14,6 +14,7 @@
14	14	unsigned char buffer[PAGE_SIZE];
15	15	unsigned int len;
16	16	unsigned int readpos;
	17	+ int full;
17	18	};
18	19
19	20	static inline void
...	...	@@ -21,6 +22,7 @@
21	22	{
22	23	s->len = 0;
23	24	s->readpos = 0;
	25	+ s->full = 0;
24	26	}
25	27
26	28	/*
...	...	@@ -93,7 +93,7 @@
93	93	va_list ap;
94	94	int ret;
95	95
96		- if (!len)
	96	+ if (s->full \|\| !len)
97	97	return 0;
98	98
99	99	va_start(ap, fmt);
100	100
...	...	@@ -101,8 +101,10 @@
101	101	va_end(ap);
102	102
103	103	/* If we can't write it all, don't bother writing anything */
104		- if (ret >= len)
	104	+ if (ret >= len) {
	105	+ s->full = 1;
105	106	return 0;
	107	+ }
106	108
107	109	s->len += ret;
108	110
109	111
110	112
...	...	@@ -127,14 +129,16 @@
127	129	int len = (PAGE_SIZE - 1) - s->len;
128	130	int ret;
129	131
130		- if (!len)
	132	+ if (s->full \|\| !len)
131	133	return 0;
132	134
133	135	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
134	136
135	137	/* If we can't write it all, don't bother writing anything */
136		- if (ret >= len)
	138	+ if (ret >= len) {
	139	+ s->full = 1;
137	140	return 0;
	141	+ }
138	142
139	143	s->len += ret;
140	144
141	145
142	146
...	...	@@ -147,14 +151,16 @@
147	151	int len = (PAGE_SIZE - 1) - s->len;
148	152	int ret;
149	153
150		- if (!len)
	154	+ if (s->full \|\| !len)
151	155	return 0;
152	156
153	157	ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
154	158
155	159	/* If we can't write it all, don't bother writing anything */
156		- if (ret >= len)
	160	+ if (ret >= len) {
	161	+ s->full = 1;
157	162	return 0;
	163	+ }
158	164
159	165	s->len += ret;
160	166
161	167
...	...	@@ -175,9 +181,14 @@
175	181	{
176	182	int len = strlen(str);
177	183
178		- if (len > ((PAGE_SIZE - 1) - s->len))
	184	+ if (s->full)
179	185	return 0;
180	186
	187	+ if (len > ((PAGE_SIZE - 1) - s->len)) {
	188	+ s->full = 1;
	189	+ return 0;
	190	+ }
	191	+
181	192	memcpy(s->buffer + s->len, str, len);
182	193	s->len += len;
183	194
184	195
...	...	@@ -186,9 +197,14 @@
186	197
187	198	int trace_seq_putc(struct trace_seq *s, unsigned char c)
188	199	{
189		- if (s->len >= (PAGE_SIZE - 1))
	200	+ if (s->full)
190	201	return 0;
191	202
	203	+ if (s->len >= (PAGE_SIZE - 1)) {
	204	+ s->full = 1;
	205	+ return 0;
	206	+ }
	207	+
192	208	s->buffer[s->len++] = c;
193	209
194	210	return 1;
195	211
...	...	@@ -196,9 +212,14 @@
196	212
197	213	int trace_seq_putmem(struct trace_seq s, const void mem, size_t len)
198	214	{
199		- if (len > ((PAGE_SIZE - 1) - s->len))
	215	+ if (s->full)
200	216	return 0;
201	217
	218	+ if (len > ((PAGE_SIZE - 1) - s->len)) {
	219	+ s->full = 1;
	220	+ return 0;
	221	+ }
	222	+
202	223	memcpy(s->buffer + s->len, mem, len);
203	224	s->len += len;
204	225
...	...	@@ -211,6 +232,9 @@
211	232	const unsigned char *data = mem;
212	233	int i, j;
213	234
	235	+ if (s->full)
	236	+ return 0;
	237	+
214	238	#ifdef __BIG_ENDIAN
215	239	for (i = 0, j = 0; i < len; i++) {
216	240	#else
217	241
...	...	@@ -228,8 +252,13 @@
228	252	{
229	253	void *ret;
230	254
231		- if (len > ((PAGE_SIZE - 1) - s->len))
	255	+ if (s->full)
	256	+ return 0;
	257	+
	258	+ if (len > ((PAGE_SIZE - 1) - s->len)) {
	259	+ s->full = 1;
232	260	return NULL;
	261	+ }
233	262
234	263	ret = s->buffer + s->len;
235	264	s->len += len;
236	265
...	...	@@ -241,8 +270,14 @@
241	270	{
242	271	unsigned char *p;
243	272
244		- if (s->len >= (PAGE_SIZE - 1))
	273	+ if (s->full)
245	274	return 0;
	275	+
	276	+ if (s->len >= (PAGE_SIZE - 1)) {
	277	+ s->full = 1;
	278	+ return 0;
	279	+ }
	280	+
246	281	p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
247	282	if (!IS_ERR(p)) {
248	283	p = mangle_path(s->buffer + s->len, p, "\n");
...	...	@@ -255,6 +290,7 @@
255	290	return 1;
256	291	}
257	292
	293	+ s->full = 1;
258	294	return 0;
259	295	}
260	296
...	...	@@ -380,6 +416,9 @@
380	416	struct file *file = NULL;
381	417	unsigned long vmstart = 0;
382	418	int ret = 1;
	419	+
	420	+ if (s->full)
	421	+ return 0;
383	422
384	423	if (mm) {
385	424	const struct vm_area_struct *vma;