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kfifo: fix kernel BUG in dma example

PATCH In review Andrea Righi 2 participants 6 messages Aug 13, 2010 Kfifo

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Andrea Righi

author
#0 lore raw

PATCH 1/3 kfifo: fix kernel BUG in dma example

The scatterlist is used uninitialized in kfifo_dma_in_prepare(). This triggers the following bug if CONFIG_DEBUG_SG=y:

  ------------[ cut here ]------------
  kernel BUG at include/linux/scatterlist.h:65!
  invalid opcode: 0000 [#1] PREEMPT SMP
  ...
  Call Trace:
   [<ffffffff810a1eab>] setup_sgl+0x6b/0xe0
   [<ffffffffa03d7000>] ? example_init+0x0/0x265 [dma_example]
   [<ffffffff810a2021>] __kfifo_dma_in_prepare+0x21/0x30
   [<ffffffffa03d7124>] example_init+0x124/0x265 [dma_example]
   [<ffffffff810f9c55>] ? trace_module_notify+0x25/0x370
   [<ffffffff81110c6e>] ? free_pages_prepare+0x11e/0x1e0
   [<ffffffff8106f2b1>] ? get_parent_ip+0x11/0x50
   [<ffffffff810f9c55>] ? trace_module_notify+0x25/0x370
   [<ffffffff810b65fd>] ? trace_hardirqs_on+0xd/0x10
   [<ffffffff814beade>] ? mutex_unlock+0xe/0x10
   [<ffffffff810f9c71>] ? trace_module_notify+0x41/0x370
   [<ffffffff810a77d5>] ? __blocking_notifier_call_chain+0x45/0x80
   [<ffffffff81137b7a>] ? vfree+0x2a/0x30
   [<ffffffff810a6ac3>] ? up_read+0x23/0x40
   [<ffffffff810a77f5>] ? __blocking_notifier_call_chain+0x65/0x80
   [<ffffffff810001e3>] do_one_initcall+0x43/0x180
   [<ffffffff810c577a>] sys_init_module+0xba/0x200
   [<ffffffff8103819b>] system_call_fastpath+0x16/0x1b
  RIP  [<ffffffff810a1e31>] setup_sgl_buf+0x1a1/0x1b0
   RSP <ffff88006720dc98>
  ---[ end trace a72b979fd3c1d3a5 ]---

Add the proper initialization to avoid the bug.

Signed-off-by Andrea Righi <[email protected]>
---
 samples/kfifo/dma-example.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
samples/kfifo/dma-example.c +1 -0
index b9482c2..03433ca 100644
@@ -45,6 +45,7 @@ static int __init example_init(void)
 
 	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
 
+	sg_init_table(sg, ARRAY_SIZE(sg));
 	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
 	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
Signature · 1 line
1.7.0.4
author
#1 lore raw

PATCH 2/3 kfifo: fix a memory leak in dma example

We use a dynamically allocated kfifo in the dma example, so we need to free it when unloading the module.

Signed-off-by Andrea Righi <[email protected]>
---
 samples/kfifo/dma-example.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
samples/kfifo/dma-example.c +1 -3
index 03433ca..3682278 100644
@@ -105,9 +105,7 @@ static int __init example_init(void)
 
 static void __exit example_exit(void)
 {
-#ifdef DYNAMIC
-	kfifo_free(&test);
-#endif
+	kfifo_free(&fifo);
 }
 
 module_init(example_init);
Signature · 1 line
1.7.0.4
maintainer Acked-by on v1 2/3
#2 lore raw

Re: [PATCH 2/3] kfifo: fix a memory leak in dma example

We use a dynamically allocated kfifo in the dma example, so we need to free it when unloading the module.

Signed-off-by Andrea Righi <[email protected]>
Acked-by Stefani Seibold <[email protected]>
---
 samples/kfifo/dma-example.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
samples/kfifo/dma-example.c +1 -3
index 03433ca..3682278 100644
@@ -105,9 +105,7 @@ static int __init example_init(void)
 
 static void __exit example_exit(void)
 {
-#ifdef DYNAMIC
-	kfifo_free(&test);
-#endif
+	kfifo_free(&fifo);
 }
 
 module_init(example_init);
author
#3 lore raw

PATCH 3/3 kfifo: add explicit error checking in all the examples

In reply to Andrea Righi

Provide a check in all the kfifo examples to validate the correct execution of each testcase.

[ Andrew: this depends on kfifo-add-explicit-error-checking-in-byte-stream-example.patch ]

Signed-off-by Andrea Righi <[email protected]>
---
 samples/kfifo/bytestream-example.c |    7 ++-
 samples/kfifo/dma-example.c        |  106 +++++++++++++++++++++++-------------
 samples/kfifo/inttype-example.c    |   43 ++++++++++++---
 samples/kfifo/record-example.c     |   39 ++++++++++++-
 4 files changed, 144 insertions(+), 51 deletions(-)
samples/kfifo/bytestream-example.c +6 -1
index a94e694..178061e 100644
@@ -44,7 +44,7 @@ static struct kfifo test;
 static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
 #endif
 
-static unsigned char expected_result[FIFO_SIZE] = {
+static const unsigned char expected_result[FIFO_SIZE] = {
 	 3,  4,  5,  6,  7,  8,  9,  0,
 	 1, 20, 21, 22, 23, 24, 25, 26,
 	27, 28, 29, 30, 31, 32, 33, 34,

@@ -90,9 +90,14 @@ static int __init testfunc(void)
 
 	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
 
+	/* show the first value without removing from the fifo */
+	if (kfifo_peek(&test, &i))
+		printk(KERN_INFO "%d\n", i);
+
 	/* check the correctness of all values in the fifo */
 	j = 0;
 	while (kfifo_get(&test, &i)) {
+		printk(KERN_INFO "item = %d\n", i);
 		if (i != expected_result[j++]) {
 			printk(KERN_WARNING "value mismatch: test failed\n");
 			return -EIO;
samples/kfifo/dma-example.c +67 -39

140 lines not on this page · raw message

samples/kfifo/inttype-example.c +35 -8

70 lines not on this page · raw message

samples/kfifo/record-example.c +36 -3
index 32c6e0b..e68bd16 100644
@@ -55,6 +55,19 @@ typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
 static mytest test;
 #endif
 
+static const char *expected_result[] = {
+	"a",
+	"bb",
+	"ccc",
+	"dddd",
+	"eeeee",
+	"ffffff",
+	"ggggggg",
+	"hhhhhhhh",
+	"iiiiiiiii",
+	"jjjjjjjjjj",
+};
+
 static int __init testfunc(void)
 {
 	char		buf[100];

@@ -75,6 +88,10 @@ static int __init testfunc(void)
 		kfifo_in(&test, buf, i + 1);
 	}
 
+	/* skip first element of the fifo */
+	printk(KERN_INFO "skip 1st element\n");
+	kfifo_skip(&test);
+
 	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
 
 	/* show the first record without removing from the fifo */

@@ -82,11 +99,22 @@ static int __init testfunc(void)
 	if (ret)
 		printk(KERN_INFO "%.*s\n", ret, buf);
 
-	/* print out all records in the fifo */
+	/* check the correctness of all values in the fifo */
+	i = 0;
 	while (!kfifo_is_empty(&test)) {
 		ret = kfifo_out(&test, buf, sizeof(buf));
-		printk(KERN_INFO "%.*s\n", ret, buf);
+		buf[ret] = '\0';
+		printk(KERN_INFO "item = %.*s\n", ret, buf);
+		if (strcmp(buf, expected_result[i++])) {
+			printk(KERN_WARNING "value mismatch: test failed\n");
+			return -EIO;
+		}
+	}
+	if (i != ARRAY_SIZE(expected_result)) {
+		printk(KERN_WARNING "size mismatch: test failed\n");
+		return -EIO;
 	}
+	printk(KERN_INFO "test passed\n");
 
 	return 0;
 }

@@ -142,7 +170,12 @@ static int __init example_init(void)
 #else
 	INIT_KFIFO(test);
 #endif
-	testfunc();
+	if (testfunc() < 0) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -EIO;
+	}
 
 	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
 #ifdef DYNAMIC
Signature · 1 line
1.7.0.4
maintainer Acked-by on v1 3/3
#4 lore raw

Re: [PATCH 3/3] kfifo: add explicit error checking in all the examples

Provide a check in all the kfifo examples to validate the correct execution of each testcase.

[ Andrew: this depends on kfifo-add-explicit-error-checking-in-byte-stream-example.patch ]

Signed-off-by Andrea Righi <[email protected]>
Acked-by Stefani Seibold <[email protected]>
---
 samples/kfifo/bytestream-example.c |    7 ++-
 samples/kfifo/dma-example.c        |  106 +++++++++++++++++++++++-------------
 samples/kfifo/inttype-example.c    |   43 ++++++++++++---
 samples/kfifo/record-example.c     |   39 ++++++++++++-
 4 files changed, 144 insertions(+), 51 deletions(-)
samples/kfifo/bytestream-example.c +6 -1
index a94e694..178061e 100644
@@ -44,7 +44,7 @@ static struct kfifo test;
 static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
 #endif
 
-static unsigned char expected_result[FIFO_SIZE] = {
+static const unsigned char expected_result[FIFO_SIZE] = {
 	 3,  4,  5,  6,  7,  8,  9,  0,
 	 1, 20, 21, 22, 23, 24, 25, 26,
 	27, 28, 29, 30, 31, 32, 33, 34,

@@ -90,9 +90,14 @@ static int __init testfunc(void)
 
 	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
 
+	/* show the first value without removing from the fifo */
+	if (kfifo_peek(&test, &i))
+		printk(KERN_INFO "%d\n", i);
+
 	/* check the correctness of all values in the fifo */
 	j = 0;
 	while (kfifo_get(&test, &i)) {
+		printk(KERN_INFO "item = %d\n", i);
 		if (i != expected_result[j++]) {
 			printk(KERN_WARNING "value mismatch: test failed\n");
 			return -EIO;
samples/kfifo/dma-example.c +67 -39

140 lines not on this page · raw message

samples/kfifo/inttype-example.c +35 -8

70 lines not on this page · raw message

samples/kfifo/record-example.c +36 -3
index 32c6e0b..e68bd16 100644
@@ -55,6 +55,19 @@ typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
 static mytest test;
 #endif
 
+static const char *expected_result[] = {
+	"a",
+	"bb",
+	"ccc",
+	"dddd",
+	"eeeee",
+	"ffffff",
+	"ggggggg",
+	"hhhhhhhh",
+	"iiiiiiiii",
+	"jjjjjjjjjj",
+};
+
 static int __init testfunc(void)
 {
 	char		buf[100];

@@ -75,6 +88,10 @@ static int __init testfunc(void)
 		kfifo_in(&test, buf, i + 1);
 	}
 
+	/* skip first element of the fifo */
+	printk(KERN_INFO "skip 1st element\n");
+	kfifo_skip(&test);
+
 	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
 
 	/* show the first record without removing from the fifo */

@@ -82,11 +99,22 @@ static int __init testfunc(void)
 	if (ret)
 		printk(KERN_INFO "%.*s\n", ret, buf);
 
-	/* print out all records in the fifo */
+	/* check the correctness of all values in the fifo */
+	i = 0;
 	while (!kfifo_is_empty(&test)) {
 		ret = kfifo_out(&test, buf, sizeof(buf));
-		printk(KERN_INFO "%.*s\n", ret, buf);
+		buf[ret] = '\0';
+		printk(KERN_INFO "item = %.*s\n", ret, buf);
+		if (strcmp(buf, expected_result[i++])) {
+			printk(KERN_WARNING "value mismatch: test failed\n");
+			return -EIO;
+		}
+	}
+	if (i != ARRAY_SIZE(expected_result)) {
+		printk(KERN_WARNING "size mismatch: test failed\n");
+		return -EIO;
 	}
+	printk(KERN_INFO "test passed\n");
 
 	return 0;
 }

@@ -142,7 +170,12 @@ static int __init example_init(void)
 #else
 	INIT_KFIFO(test);
 #endif
-	testfunc();
+	if (testfunc() < 0) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -EIO;
+	}
 
 	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
 #ifdef DYNAMIC
maintainer Acked-by on v1 1/3
#5 lore raw
In reply to Andrea Righi

The scatterlist is used uninitialized in kfifo_dma_in_prepare(). This triggers the following bug if CONFIG_DEBUG_SG=y:

  ------------[ cut here ]------------
  kernel BUG at include/linux/scatterlist.h:65!
  invalid opcode: 0000 [#1] PREEMPT SMP
  ...
  Call Trace:
   [<ffffffff810a1eab>] setup_sgl+0x6b/0xe0
   [<ffffffffa03d7000>] ? example_init+0x0/0x265 [dma_example]
   [<ffffffff810a2021>] __kfifo_dma_in_prepare+0x21/0x30
   [<ffffffffa03d7124>] example_init+0x124/0x265 [dma_example]
   [<ffffffff810f9c55>] ? trace_module_notify+0x25/0x370
   [<ffffffff81110c6e>] ? free_pages_prepare+0x11e/0x1e0
   [<ffffffff8106f2b1>] ? get_parent_ip+0x11/0x50
   [<ffffffff810f9c55>] ? trace_module_notify+0x25/0x370
   [<ffffffff810b65fd>] ? trace_hardirqs_on+0xd/0x10
   [<ffffffff814beade>] ? mutex_unlock+0xe/0x10
   [<ffffffff810f9c71>] ? trace_module_notify+0x41/0x370
   [<ffffffff810a77d5>] ? __blocking_notifier_call_chain+0x45/0x80
   [<ffffffff81137b7a>] ? vfree+0x2a/0x30
   [<ffffffff810a6ac3>] ? up_read+0x23/0x40
   [<ffffffff810a77f5>] ? __blocking_notifier_call_chain+0x65/0x80
   [<ffffffff810001e3>] do_one_initcall+0x43/0x180
   [<ffffffff810c577a>] sys_init_module+0xba/0x200
   [<ffffffff8103819b>] system_call_fastpath+0x16/0x1b
  RIP  [<ffffffff810a1e31>] setup_sgl_buf+0x1a1/0x1b0
   RSP <ffff88006720dc98>
  ---[ end trace a72b979fd3c1d3a5 ]---

Add the proper initialization to avoid the bug.

Signed-off-by Andrea Righi <[email protected]>
Acked-by Stefani Seibold <[email protected]>
---
 samples/kfifo/dma-example.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
samples/kfifo/dma-example.c +1 -0
index b9482c2..03433ca 100644
@@ -45,6 +45,7 @@ static int __init example_init(void)
 
 	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
 
+	sg_init_table(sg, ARRAY_SIZE(sg));
 	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
 	printk(KERN_INFO "DMA sgl entries: %d\n", ret);