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authorJoerg Roedel <joerg.roedel@amd.com>2009-05-22 15:23:13 -0400
committerJoerg Roedel <joerg.roedel@amd.com>2009-06-02 10:21:18 -0400
commit8a6fc708b9bb48a79a385bdc2be0959ee2ab788d (patch)
tree55db1582e9d14092855ef28a050fb1913d76667c /lib
parent2e507d849f1834d3fe9aae71b7aabf4c2a3827b8 (diff)
dma-debug: add debugfs file for driver filter
This patch adds the dma-api/driver_filter file to debugfs. The root user can write a driver name into this file to see only dma-api errors for that particular driver in the kernel log. Writing an empty string to that file disables the driver filter. Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Diffstat (limited to 'lib')
-rw-r--r--lib/dma-debug.c102
1 files changed, 101 insertions, 1 deletions
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index c01f64780ca..c6330b1a7be 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -23,9 +23,11 @@
23#include <linux/dma-debug.h> 23#include <linux/dma-debug.h>
24#include <linux/spinlock.h> 24#include <linux/spinlock.h>
25#include <linux/debugfs.h> 25#include <linux/debugfs.h>
26#include <linux/uaccess.h>
26#include <linux/device.h> 27#include <linux/device.h>
27#include <linux/types.h> 28#include <linux/types.h>
28#include <linux/sched.h> 29#include <linux/sched.h>
30#include <linux/ctype.h>
29#include <linux/list.h> 31#include <linux/list.h>
30#include <linux/slab.h> 32#include <linux/slab.h>
31 33
@@ -98,6 +100,7 @@ static struct dentry *show_all_errors_dent __read_mostly;
98static struct dentry *show_num_errors_dent __read_mostly; 100static struct dentry *show_num_errors_dent __read_mostly;
99static struct dentry *num_free_entries_dent __read_mostly; 101static struct dentry *num_free_entries_dent __read_mostly;
100static struct dentry *min_free_entries_dent __read_mostly; 102static struct dentry *min_free_entries_dent __read_mostly;
103static struct dentry *filter_dent __read_mostly;
101 104
102/* per-driver filter related state */ 105/* per-driver filter related state */
103 106
@@ -160,7 +163,8 @@ static bool driver_filter(struct device *dev)
160 read_lock_irqsave(&driver_name_lock, flags); 163 read_lock_irqsave(&driver_name_lock, flags);
161 164
162 if (drv->name && 165 if (drv->name &&
163 strncmp(current_driver_name, drv->name, 63) == 0) { 166 strncmp(current_driver_name, drv->name,
167 NAME_MAX_LEN-1) == 0) {
164 current_driver = drv; 168 current_driver = drv;
165 ret = true; 169 ret = true;
166 } 170 }
@@ -454,6 +458,97 @@ out_err:
454 return -ENOMEM; 458 return -ENOMEM;
455} 459}
456 460
461static ssize_t filter_read(struct file *file, char __user *user_buf,
462 size_t count, loff_t *ppos)
463{
464 unsigned long flags;
465 char buf[NAME_MAX_LEN + 1];
466 int len;
467
468 if (!current_driver_name[0])
469 return 0;
470
471 /*
472 * We can't copy to userspace directly because current_driver_name can
473 * only be read under the driver_name_lock with irqs disabled. So
474 * create a temporary copy first.
475 */
476 read_lock_irqsave(&driver_name_lock, flags);
477 len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
478 read_unlock_irqrestore(&driver_name_lock, flags);
479
480 return simple_read_from_buffer(user_buf, count, ppos, buf, len);
481}
482
483static ssize_t filter_write(struct file *file, const char __user *userbuf,
484 size_t count, loff_t *ppos)
485{
486 unsigned long flags;
487 char buf[NAME_MAX_LEN];
488 size_t len = NAME_MAX_LEN - 1;
489 int i;
490
491 /*
492 * We can't copy from userspace directly. Access to
493 * current_driver_name is protected with a write_lock with irqs
494 * disabled. Since copy_from_user can fault and may sleep we
495 * need to copy to temporary buffer first
496 */
497 len = min(count, len);
498 if (copy_from_user(buf, userbuf, len))
499 return -EFAULT;
500
501 buf[len] = 0;
502
503 write_lock_irqsave(&driver_name_lock, flags);
504
505 /* Now handle the string we got from userspace very carefully.
506 * The rules are:
507 * - only use the first token we got
508 * - token delimiter is everything looking like a space
509 * character (' ', '\n', '\t' ...)
510 *
511 */
512 if (!isalnum(buf[0])) {
513 /*
514 If the first character userspace gave us is not
515 * alphanumerical then assume the filter should be
516 * switched off.
517 */
518 if (current_driver_name[0])
519 printk(KERN_INFO "DMA-API: switching off dma-debug "
520 "driver filter\n");
521 current_driver_name[0] = 0;
522 current_driver = NULL;
523 goto out_unlock;
524 }
525
526 /*
527 * Now parse out the first token and use it as the name for the
528 * driver to filter for.
529 */
530 for (i = 0; i < NAME_MAX_LEN; ++i) {
531 current_driver_name[i] = buf[i];
532 if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
533 break;
534 }
535 current_driver_name[i] = 0;
536 current_driver = NULL;
537
538 printk(KERN_INFO "DMA-API: enable driver filter for driver [%s]\n",
539 current_driver_name);
540
541out_unlock:
542 write_unlock_irqrestore(&driver_name_lock, flags);
543
544 return count;
545}
546
547const struct file_operations filter_fops = {
548 .read = filter_read,
549 .write = filter_write,
550};
551
457static int dma_debug_fs_init(void) 552static int dma_debug_fs_init(void)
458{ 553{
459 dma_debug_dent = debugfs_create_dir("dma-api", NULL); 554 dma_debug_dent = debugfs_create_dir("dma-api", NULL);
@@ -497,6 +592,11 @@ static int dma_debug_fs_init(void)
497 if (!min_free_entries_dent) 592 if (!min_free_entries_dent)
498 goto out_err; 593 goto out_err;
499 594
595 filter_dent = debugfs_create_file("driver_filter", 0644,
596 dma_debug_dent, NULL, &filter_fops);
597 if (!filter_dent)
598 goto out_err;
599
500 return 0; 600 return 0;
501 601
502out_err: 602out_err: