From: Shuah Khan <shuah.khan@hp.com>
To: joerg.roedel@amd.com, paul.gortmaker@windriver.com,
kubakici@wp.pl, stern@rowland.harvard.edu,
dan.carpenter@oracle.com,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
rob@landley.net
Cc: linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
shuahkhan@gmail.com
Subject: [PATCH] dma-debug: Add dma map/unmap error tracking support
Date: Sun, 02 Sep 2012 08:14:17 -0600 [thread overview]
Message-ID: <1346595257.4377.5.camel@lorien2> (raw)
A recent dma mapping error analysis effort showed that a large precentage
of dma_map_single() and dma_map_page() returns are not checked for mapping
errors. Reference: https://lkml.org/lkml/2012/8/10/326
Adding support for tracking dma mapping and unmapping errors to help assess
the following:
When do dma mapping errors get detected?
How often do these errors occur?
Why don't we see failures related to missing dma mapping error checks?
Are they silent failures?
Signed-off-by: Shuah Khan <shuah.khan@hp.com>
---
Documentation/DMA-API.txt | 7 +++++++
lib/dma-debug.c | 26 +++++++++++++++++++++++++-
2 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 66bd97a..ee10a11 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -638,6 +638,13 @@ this directory the following files can currently be found:
dma-api/error_count This file is read-only and shows the total
numbers of errors found.
+ dma-api/dma_map_errors This file is read-only and shows the total
+ number of dma mapping errors detected.
+
+ dma-api/dma_unmap_errors
+ This file is read-only and shows the total
+ number of invalid dma unmapping attempts.
+
dma-api/num_errors The number in this file shows how many
warnings will be printed to the kernel log
before it stops. This number is initialized to
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 66ce414..8596114 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -83,6 +83,10 @@ static u32 global_disable __read_mostly;
/* Global error count */
static u32 error_count;
+/* dma mapping error counts */
+static u32 dma_map_errors;
+static u32 dma_unmap_errors;
+
/* Global error show enable*/
static u32 show_all_errors __read_mostly;
/* Number of errors to show */
@@ -104,6 +108,8 @@ static struct dentry *show_num_errors_dent __read_mostly;
static struct dentry *num_free_entries_dent __read_mostly;
static struct dentry *min_free_entries_dent __read_mostly;
static struct dentry *filter_dent __read_mostly;
+static struct dentry *dma_map_errors_dent __read_mostly;
+static struct dentry *dma_unmap_errors_dent __read_mostly;
/* per-driver filter related state */
@@ -695,6 +701,19 @@ static int dma_debug_fs_init(void)
if (!filter_dent)
goto out_err;
+ dma_map_errors_dent = debugfs_create_u32("dma_map_errors", 0444,
+ dma_debug_dent,
+ &dma_map_errors);
+
+ if (!dma_map_errors_dent)
+ goto out_err;
+
+ dma_unmap_errors_dent = debugfs_create_u32("dma_unmap_errors", 0444,
+ dma_debug_dent,
+ &dma_unmap_errors);
+ if (!dma_unmap_errors_dent)
+ goto out_err;
+
return 0;
out_err:
@@ -850,6 +869,7 @@ static void check_unmap(struct dma_debug_entry *ref)
unsigned long flags;
if (dma_mapping_error(ref->dev, ref->dev_addr)) {
+ dma_unmap_errors += 1;
err_printk(ref->dev, NULL, "DMA-API: device driver tries "
"to free an invalid DMA memory address\n");
return;
@@ -1022,8 +1042,12 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
if (unlikely(global_disable))
return;
- if (unlikely(dma_mapping_error(dev, dma_addr)))
+ if (unlikely(dma_mapping_error(dev, dma_addr))) {
+ dma_map_errors += 1;
+ err_printk(dev, NULL,
+ "DMA-API: dma_map_page() returned error\n");
return;
+ }
entry = dma_entry_alloc();
if (!entry)
--
1.7.9.5
next reply other threads:[~2012-09-02 14:14 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-02 14:14 Shuah Khan [this message]
2012-09-04 21:05 ` [PATCH] dma-debug: Add dma map/unmap error tracking support Konrad Rzeszutek Wilk
2012-09-04 22:57 ` Shuah Khan
2012-09-05 11:57 ` Konrad Rzeszutek Wilk
2012-09-05 14:34 ` Shuah Khan
2012-09-05 19:30 ` Shuah Khan
2012-09-07 15:53 ` [RFC] DMA mapping error check analysis Shuah Khan
2012-09-07 16:20 ` Alan Stern
2012-09-07 16:54 ` Shuah Khan
2012-09-10 7:53 ` Clemens Ladisch
2012-09-10 15:26 ` Shuah Khan
2012-09-10 17:17 ` Stefan Richter
2012-09-10 17:42 ` Clemens Ladisch
2012-09-10 19:28 ` Stefan Richter
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