[PATCH v5] dma-debug: New interfaces to debug dma mapping errors

[PATCH v5] dma-debug: New interfaces to debug dma mapping errors

[Shuah Khan]

Add dma-debug interface debug_dma_mapping_error() to debug drivers that fail
to check dma mapping errors on addresses returned by dma_map_single() and
dma_map_page() interfaces. This interface clears a flag set by
debug_dma_map_page() to indicate that dma_mapping_error() has been called by
the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
this flag is still set, prints warning message that includes call trace that
leads up to the unmap. This interface can be called from dma_mapping_error()
routines to enable dma mapping error check debugging.

Tested: Intel iommu and swiotlb (iommu=soft) on x86-64 with
        CONFIG_DMA_API_DEBUG enabled and disabled.

Signed-off-by: Shuah Khan <shuah.khan@hp.com>
---
 Documentation/DMA-API.txt          |   12 ++++++
 arch/x86/include/asm/dma-mapping.h |    1 +
 include/linux/dma-debug.h          |    7 ++++
 lib/dma-debug.c                    |   71 ++++++++++++++++++++++++++++++++++--
 4 files changed, 87 insertions(+), 4 deletions(-)

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 66bd97a..78a6c56 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -678,3 +678,15 @@ out of dma_debug_entries. These entries are preallocated at boot. The number
 of preallocated entries is defined per architecture. If it is too low for you
 boot with 'dma_debug_entries=<your_desired_number>' to overwrite the
 architectural default.
+
+void debug_dmap_mapping_error(struct device *dev, dma_addr_t dma_addr);
+
+dma-debug interface debug_dma_mapping_error() to debug drivers that fail
+to check dma mapping errors on addresses returned by dma_map_single() and
+dma_map_page() interfaces. This interface clears a flag set by
+debug_dma_map_page() to indicate that dma_mapping_error() has been called by
+the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
+this flag is still set, prints warning message that includes call trace that
+leads up to the unmap. This interface can be called from dma_mapping_error()
+routines to enable dma mapping error check debugging.
+
diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
index f7b4c79..808dae6 100644
--- a/arch/x86/include/asm/dma-mapping.h
+++ b/arch/x86/include/asm/dma-mapping.h
@@ -47,6 +47,7 @@ static inline struct dma_map_ops *get_dma_ops(struct device *dev)
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
 	struct dma_map_ops *ops = get_dma_ops(dev);
+	debug_dma_mapping_error(dev, dma_addr);
 	if (ops->mapping_error)
 		return ops->mapping_error(dev, dma_addr);
 
diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
index 171ad8a..fc0e34c 100644
--- a/include/linux/dma-debug.h
+++ b/include/linux/dma-debug.h
@@ -39,6 +39,8 @@ extern void debug_dma_map_page(struct device *dev, struct page *page,
 			       int direction, dma_addr_t dma_addr,
 			       bool map_single);
 
+extern void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
+
 extern void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
 				 size_t size, int direction, bool map_single);
 
@@ -105,6 +107,11 @@ static inline void debug_dma_map_page(struct device *dev, struct page *page,
 {
 }
 
+static inline void debug_dma_mapping_error(struct device *dev,
+					  dma_addr_t dma_addr)
+{
+}
+
 static inline void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
 					size_t size, int direction,
 					bool map_single)
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index b9087bf..94aa94e 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -45,6 +45,12 @@ enum {
 	dma_debug_coherent,
 };
 
+enum map_err_types {
+	MAP_ERR_CHECK_NOT_APPLICABLE,
+	MAP_ERR_NOT_CHECKED,
+	MAP_ERR_CHECKED,
+};
+
 #define DMA_DEBUG_STACKTRACE_ENTRIES 5
 
 struct dma_debug_entry {
@@ -57,6 +63,7 @@ struct dma_debug_entry {
 	int              direction;
 	int		 sg_call_ents;
 	int		 sg_mapped_ents;
+	enum map_err_types  map_err_type;
 #ifdef CONFIG_STACKTRACE
 	struct		 stack_trace stacktrace;
 	unsigned long	 st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
@@ -114,6 +121,12 @@ static struct device_driver *current_driver                    __read_mostly;
 
 static DEFINE_RWLOCK(driver_name_lock);
 
+static const char *const maperr2str[] = {
+	[MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
+	[MAP_ERR_NOT_CHECKED] = "dma map error not checked",
+	[MAP_ERR_CHECKED] = "dma map error checked",
+};
+
 static const char *type2name[4] = { "single", "page",
 				    "scather-gather", "coherent" };
 
@@ -376,11 +389,12 @@ void debug_dma_dump_mappings(struct device *dev)
 		list_for_each_entry(entry, &bucket->list, list) {
 			if (!dev || dev == entry->dev) {
 				dev_info(entry->dev,
-					 "%s idx %d P=%Lx D=%Lx L=%Lx %s\n",
+					 "%s idx %d P=%Lx D=%Lx L=%Lx %s %s\n",
 					 type2name[entry->type], idx,
 					 (unsigned long long)entry->paddr,
 					 entry->dev_addr, entry->size,
-					 dir2name[entry->direction]);
+					 dir2name[entry->direction],
+					 maperr2str[entry->map_err_type]);
 			}
 		}
 
@@ -838,13 +852,28 @@ static __init int dma_debug_entries_cmdline(char *str)
 __setup("dma_debug=", dma_debug_cmdline);
 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
 
+/* Calling dma_mapping_error() from dma-debug api will result in calling
+   debug_dma_mapping_error() - need internal mapping error routine to
+   avoid debug checks */
+#ifndef DMA_ERROR_CODE
+#define DMA_ERROR_CODE 0
+#endif
+static inline int has_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+	if (ops->mapping_error)
+		return ops->mapping_error(dev, dma_addr);
+
+	return (dma_addr == DMA_ERROR_CODE);
+}
+
 static void check_unmap(struct dma_debug_entry *ref)
 {
 	struct dma_debug_entry *entry;
 	struct hash_bucket *bucket;
 	unsigned long flags;
 
-	if (dma_mapping_error(ref->dev, ref->dev_addr)) {
+	if (unlikely(has_mapping_error(ref->dev, ref->dev_addr))) {
 		err_printk(ref->dev, NULL, "DMA-API: device driver tries "
 			   "to free an invalid DMA memory address\n");
 		return;
@@ -910,6 +939,15 @@ static void check_unmap(struct dma_debug_entry *ref)
 			   dir2name[ref->direction]);
 	}
 
+	if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
+		err_printk(ref->dev, entry,
+			   "DMA-API: device driver failed to check map error"
+			   "[device address=0x%016llx] [size=%llu bytes] "
+			   "[mapped as %s]",
+			   ref->dev_addr, ref->size,
+			   type2name[entry->type]);
+	}
+
 	hash_bucket_del(entry);
 	dma_entry_free(entry);
 
@@ -1017,7 +1055,7 @@ 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(has_mapping_error(dev, dma_addr)))
 		return;
 
 	entry = dma_entry_alloc();
@@ -1030,6 +1068,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
 	entry->dev_addr  = dma_addr;
 	entry->size      = size;
 	entry->direction = direction;
+	entry->map_err_type = MAP_ERR_NOT_CHECKED;
 
 	if (map_single)
 		entry->type = dma_debug_single;
@@ -1045,6 +1084,30 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
 }
 EXPORT_SYMBOL(debug_dma_map_page);
 
+void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+	struct dma_debug_entry ref;
+	struct dma_debug_entry *entry;
+	struct hash_bucket *bucket;
+	unsigned long flags;
+
+	if (unlikely(global_disable))
+		return;
+
+	ref.dev = dev;
+	ref.dev_addr = dma_addr;
+	bucket = get_hash_bucket(&ref, &flags);
+	entry = bucket_find_exact(bucket, &ref);
+
+	if (!entry)
+		goto out;
+
+	entry->map_err_type = MAP_ERR_CHECKED;
+out:
+	put_hash_bucket(bucket, &flags);
+}
+EXPORT_SYMBOL(debug_dma_mapping_error);
+
 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
 			  size_t size, int direction, bool map_single)
 {
-- 
1.7.9.5

Re: [PATCH v5] dma-debug: New interfaces to debug dma mapping errors

[Konrad Rzeszutek Wilk]

On Mon, Oct 08, 2012 at 11:08:06AM -0600, Shuah Khan wrote:
> Add dma-debug interface debug_dma_mapping_error() to debug drivers that fail
> to check dma mapping errors on addresses returned by dma_map_single() and
> dma_map_page() interfaces. This interface clears a flag set by
> debug_dma_map_page() to indicate that dma_mapping_error() has been called by
> the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
> this flag is still set, prints warning message that includes call trace that
> leads up to the unmap. This interface can be called from dma_mapping_error()
> routines to enable dma mapping error check debugging.
> 
> Tested: Intel iommu and swiotlb (iommu=soft) on x86-64 with
>         CONFIG_DMA_API_DEBUG enabled and disabled.
> 
> Signed-off-by: Shuah Khan <shuah.khan@hp.com>

Not sure why it disappeared, but:

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  Documentation/DMA-API.txt          |   12 ++++++
>  arch/x86/include/asm/dma-mapping.h |    1 +
>  include/linux/dma-debug.h          |    7 ++++
>  lib/dma-debug.c                    |   71 ++++++++++++++++++++++++++++++++++--
>  4 files changed, 87 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
> index 66bd97a..78a6c56 100644
> --- a/Documentation/DMA-API.txt
> +++ b/Documentation/DMA-API.txt
> @@ -678,3 +678,15 @@ out of dma_debug_entries. These entries are preallocated at boot. The number
>  of preallocated entries is defined per architecture. If it is too low for you
>  boot with 'dma_debug_entries=<your_desired_number>' to overwrite the
>  architectural default.
> +
> +void debug_dmap_mapping_error(struct device *dev, dma_addr_t dma_addr);
> +
> +dma-debug interface debug_dma_mapping_error() to debug drivers that fail
> +to check dma mapping errors on addresses returned by dma_map_single() and
> +dma_map_page() interfaces. This interface clears a flag set by
> +debug_dma_map_page() to indicate that dma_mapping_error() has been called by
> +the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
> +this flag is still set, prints warning message that includes call trace that
> +leads up to the unmap. This interface can be called from dma_mapping_error()
> +routines to enable dma mapping error check debugging.
> +
> diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
> index f7b4c79..808dae6 100644
> --- a/arch/x86/include/asm/dma-mapping.h
> +++ b/arch/x86/include/asm/dma-mapping.h
> @@ -47,6 +47,7 @@ static inline struct dma_map_ops *get_dma_ops(struct device *dev)
>  static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
>  {
>  	struct dma_map_ops *ops = get_dma_ops(dev);
> +	debug_dma_mapping_error(dev, dma_addr);
>  	if (ops->mapping_error)
>  		return ops->mapping_error(dev, dma_addr);
>  
> diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
> index 171ad8a..fc0e34c 100644
> --- a/include/linux/dma-debug.h
> +++ b/include/linux/dma-debug.h
> @@ -39,6 +39,8 @@ extern void debug_dma_map_page(struct device *dev, struct page *page,
>  			       int direction, dma_addr_t dma_addr,
>  			       bool map_single);
>  
> +extern void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
> +
>  extern void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
>  				 size_t size, int direction, bool map_single);
>  
> @@ -105,6 +107,11 @@ static inline void debug_dma_map_page(struct device *dev, struct page *page,
>  {
>  }
>  
> +static inline void debug_dma_mapping_error(struct device *dev,
> +					  dma_addr_t dma_addr)
> +{
> +}
> +
>  static inline void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
>  					size_t size, int direction,
>  					bool map_single)
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index b9087bf..94aa94e 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -45,6 +45,12 @@ enum {
>  	dma_debug_coherent,
>  };
>  
> +enum map_err_types {
> +	MAP_ERR_CHECK_NOT_APPLICABLE,
> +	MAP_ERR_NOT_CHECKED,
> +	MAP_ERR_CHECKED,
> +};
> +
>  #define DMA_DEBUG_STACKTRACE_ENTRIES 5
>  
>  struct dma_debug_entry {
> @@ -57,6 +63,7 @@ struct dma_debug_entry {
>  	int              direction;
>  	int		 sg_call_ents;
>  	int		 sg_mapped_ents;
> +	enum map_err_types  map_err_type;
>  #ifdef CONFIG_STACKTRACE
>  	struct		 stack_trace stacktrace;
>  	unsigned long	 st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
> @@ -114,6 +121,12 @@ static struct device_driver *current_driver                    __read_mostly;
>  
>  static DEFINE_RWLOCK(driver_name_lock);
>  
> +static const char *const maperr2str[] = {
> +	[MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
> +	[MAP_ERR_NOT_CHECKED] = "dma map error not checked",
> +	[MAP_ERR_CHECKED] = "dma map error checked",
> +};
> +
>  static const char *type2name[4] = { "single", "page",
>  				    "scather-gather", "coherent" };
>  
> @@ -376,11 +389,12 @@ void debug_dma_dump_mappings(struct device *dev)
>  		list_for_each_entry(entry, &bucket->list, list) {
>  			if (!dev || dev == entry->dev) {
>  				dev_info(entry->dev,
> -					 "%s idx %d P=%Lx D=%Lx L=%Lx %s\n",
> +					 "%s idx %d P=%Lx D=%Lx L=%Lx %s %s\n",
>  					 type2name[entry->type], idx,
>  					 (unsigned long long)entry->paddr,
>  					 entry->dev_addr, entry->size,
> -					 dir2name[entry->direction]);
> +					 dir2name[entry->direction],
> +					 maperr2str[entry->map_err_type]);
>  			}
>  		}
>  
> @@ -838,13 +852,28 @@ static __init int dma_debug_entries_cmdline(char *str)
>  __setup("dma_debug=", dma_debug_cmdline);
>  __setup("dma_debug_entries=", dma_debug_entries_cmdline);
>  
> +/* Calling dma_mapping_error() from dma-debug api will result in calling
> +   debug_dma_mapping_error() - need internal mapping error routine to
> +   avoid debug checks */
> +#ifndef DMA_ERROR_CODE
> +#define DMA_ERROR_CODE 0
> +#endif
> +static inline int has_mapping_error(struct device *dev, dma_addr_t dma_addr)
> +{
> +	const struct dma_map_ops *ops = get_dma_ops(dev);
> +	if (ops->mapping_error)
> +		return ops->mapping_error(dev, dma_addr);
> +
> +	return (dma_addr == DMA_ERROR_CODE);
> +}
> +
>  static void check_unmap(struct dma_debug_entry *ref)
>  {
>  	struct dma_debug_entry *entry;
>  	struct hash_bucket *bucket;
>  	unsigned long flags;
>  
> -	if (dma_mapping_error(ref->dev, ref->dev_addr)) {
> +	if (unlikely(has_mapping_error(ref->dev, ref->dev_addr))) {
>  		err_printk(ref->dev, NULL, "DMA-API: device driver tries "
>  			   "to free an invalid DMA memory address\n");
>  		return;
> @@ -910,6 +939,15 @@ static void check_unmap(struct dma_debug_entry *ref)
>  			   dir2name[ref->direction]);
>  	}
>  
> +	if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
> +		err_printk(ref->dev, entry,
> +			   "DMA-API: device driver failed to check map error"
> +			   "[device address=0x%016llx] [size=%llu bytes] "
> +			   "[mapped as %s]",
> +			   ref->dev_addr, ref->size,
> +			   type2name[entry->type]);
> +	}
> +
>  	hash_bucket_del(entry);
>  	dma_entry_free(entry);
>  
> @@ -1017,7 +1055,7 @@ 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(has_mapping_error(dev, dma_addr)))
>  		return;
>  
>  	entry = dma_entry_alloc();
> @@ -1030,6 +1068,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
>  	entry->dev_addr  = dma_addr;
>  	entry->size      = size;
>  	entry->direction = direction;
> +	entry->map_err_type = MAP_ERR_NOT_CHECKED;
>  
>  	if (map_single)
>  		entry->type = dma_debug_single;
> @@ -1045,6 +1084,30 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
>  }
>  EXPORT_SYMBOL(debug_dma_map_page);
>  
> +void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
> +{
> +	struct dma_debug_entry ref;
> +	struct dma_debug_entry *entry;
> +	struct hash_bucket *bucket;
> +	unsigned long flags;
> +
> +	if (unlikely(global_disable))
> +		return;
> +
> +	ref.dev = dev;
> +	ref.dev_addr = dma_addr;
> +	bucket = get_hash_bucket(&ref, &flags);
> +	entry = bucket_find_exact(bucket, &ref);
> +
> +	if (!entry)
> +		goto out;
> +
> +	entry->map_err_type = MAP_ERR_CHECKED;
> +out:
> +	put_hash_bucket(bucket, &flags);
> +}
> +EXPORT_SYMBOL(debug_dma_mapping_error);
> +
>  void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
>  			  size_t size, int direction, bool map_single)
>  {
> -- 
> 1.7.9.5
> 
> 

Re: [PATCH v5] dma-debug: New interfaces to debug dma mapping errors

[Shuah Khan]

On Tue, 2012-10-09 at 13:12 -0400, Konrad Rzeszutek Wilk wrote:
> On Mon, Oct 08, 2012 at 11:08:06AM -0600, Shuah Khan wrote:
> > Add dma-debug interface debug_dma_mapping_error() to debug drivers that fail
> > to check dma mapping errors on addresses returned by dma_map_single() and
> > dma_map_page() interfaces. This interface clears a flag set by
> > debug_dma_map_page() to indicate that dma_mapping_error() has been called by
> > the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
> > this flag is still set, prints warning message that includes call trace that
> > leads up to the unmap. This interface can be called from dma_mapping_error()
> > routines to enable dma mapping error check debugging.
> > 
> > Tested: Intel iommu and swiotlb (iommu=soft) on x86-64 with
> >         CONFIG_DMA_API_DEBUG enabled and disabled.
> > 
> > Signed-off-by: Shuah Khan <shuah.khan@hp.com>
> 
> Not sure why it disappeared, but:
> 
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Sorry, my bad. Thanks.

> > ---
> >  Documentation/DMA-API.txt          |   12 ++++++
> >  arch/x86/include/asm/dma-mapping.h |    1 +
> >  include/linux/dma-debug.h          |    7 ++++
> >  lib/dma-debug.c                    |   71 ++++++++++++++++++++++++++++++++++--
> >  4 files changed, 87 insertions(+), 4 deletions(-)
> > 
> > diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
> > index 66bd97a..78a6c56 100644
> > --- a/Documentation/DMA-API.txt
> > +++ b/Documentation/DMA-API.txt
> > @@ -678,3 +678,15 @@ out of dma_debug_entries. These entries are preallocated at boot. The number
> >  of preallocated entries is defined per architecture. If it is too low for you
> >  boot with 'dma_debug_entries=<your_desired_number>' to overwrite the
> >  architectural default.
> > +
> > +void debug_dmap_mapping_error(struct device *dev, dma_addr_t dma_addr);
> > +
> > +dma-debug interface debug_dma_mapping_error() to debug drivers that fail
> > +to check dma mapping errors on addresses returned by dma_map_single() and
> > +dma_map_page() interfaces. This interface clears a flag set by
> > +debug_dma_map_page() to indicate that dma_mapping_error() has been called by
> > +the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
> > +this flag is still set, prints warning message that includes call trace that
> > +leads up to the unmap. This interface can be called from dma_mapping_error()
> > +routines to enable dma mapping error check debugging.
> > +
> > diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
> > index f7b4c79..808dae6 100644
> > --- a/arch/x86/include/asm/dma-mapping.h
> > +++ b/arch/x86/include/asm/dma-mapping.h
> > @@ -47,6 +47,7 @@ static inline struct dma_map_ops *get_dma_ops(struct device *dev)
> >  static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
> >  {
> >  	struct dma_map_ops *ops = get_dma_ops(dev);
> > +	debug_dma_mapping_error(dev, dma_addr);
> >  	if (ops->mapping_error)
> >  		return ops->mapping_error(dev, dma_addr);
> >  
> > diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
> > index 171ad8a..fc0e34c 100644
> > --- a/include/linux/dma-debug.h
> > +++ b/include/linux/dma-debug.h
> > @@ -39,6 +39,8 @@ extern void debug_dma_map_page(struct device *dev, struct page *page,
> >  			       int direction, dma_addr_t dma_addr,
> >  			       bool map_single);
> >  
> > +extern void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
> > +
> >  extern void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
> >  				 size_t size, int direction, bool map_single);
> >  
> > @@ -105,6 +107,11 @@ static inline void debug_dma_map_page(struct device *dev, struct page *page,
> >  {
> >  }
> >  
> > +static inline void debug_dma_mapping_error(struct device *dev,
> > +					  dma_addr_t dma_addr)
> > +{
> > +}
> > +
> >  static inline void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
> >  					size_t size, int direction,
> >  					bool map_single)
> > diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> > index b9087bf..94aa94e 100644
> > --- a/lib/dma-debug.c
> > +++ b/lib/dma-debug.c
> > @@ -45,6 +45,12 @@ enum {
> >  	dma_debug_coherent,
> >  };
> >  
> > +enum map_err_types {
> > +	MAP_ERR_CHECK_NOT_APPLICABLE,
> > +	MAP_ERR_NOT_CHECKED,
> > +	MAP_ERR_CHECKED,
> > +};
> > +
> >  #define DMA_DEBUG_STACKTRACE_ENTRIES 5
> >  
> >  struct dma_debug_entry {
> > @@ -57,6 +63,7 @@ struct dma_debug_entry {
> >  	int              direction;
> >  	int		 sg_call_ents;
> >  	int		 sg_mapped_ents;
> > +	enum map_err_types  map_err_type;
> >  #ifdef CONFIG_STACKTRACE
> >  	struct		 stack_trace stacktrace;
> >  	unsigned long	 st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
> > @@ -114,6 +121,12 @@ static struct device_driver *current_driver                    __read_mostly;
> >  
> >  static DEFINE_RWLOCK(driver_name_lock);
> >  
> > +static const char *const maperr2str[] = {
> > +	[MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
> > +	[MAP_ERR_NOT_CHECKED] = "dma map error not checked",
> > +	[MAP_ERR_CHECKED] = "dma map error checked",
> > +};
> > +
> >  static const char *type2name[4] = { "single", "page",
> >  				    "scather-gather", "coherent" };
> >  
> > @@ -376,11 +389,12 @@ void debug_dma_dump_mappings(struct device *dev)
> >  		list_for_each_entry(entry, &bucket->list, list) {
> >  			if (!dev || dev == entry->dev) {
> >  				dev_info(entry->dev,
> > -					 "%s idx %d P=%Lx D=%Lx L=%Lx %s\n",
> > +					 "%s idx %d P=%Lx D=%Lx L=%Lx %s %s\n",
> >  					 type2name[entry->type], idx,
> >  					 (unsigned long long)entry->paddr,
> >  					 entry->dev_addr, entry->size,
> > -					 dir2name[entry->direction]);
> > +					 dir2name[entry->direction],
> > +					 maperr2str[entry->map_err_type]);
> >  			}
> >  		}
> >  
> > @@ -838,13 +852,28 @@ static __init int dma_debug_entries_cmdline(char *str)
> >  __setup("dma_debug=", dma_debug_cmdline);
> >  __setup("dma_debug_entries=", dma_debug_entries_cmdline);
> >  
> > +/* Calling dma_mapping_error() from dma-debug api will result in calling
> > +   debug_dma_mapping_error() - need internal mapping error routine to
> > +   avoid debug checks */
> > +#ifndef DMA_ERROR_CODE
> > +#define DMA_ERROR_CODE 0
> > +#endif
> > +static inline int has_mapping_error(struct device *dev, dma_addr_t dma_addr)
> > +{
> > +	const struct dma_map_ops *ops = get_dma_ops(dev);
> > +	if (ops->mapping_error)
> > +		return ops->mapping_error(dev, dma_addr);
> > +
> > +	return (dma_addr == DMA_ERROR_CODE);
> > +}
> > +
> >  static void check_unmap(struct dma_debug_entry *ref)
> >  {
> >  	struct dma_debug_entry *entry;
> >  	struct hash_bucket *bucket;
> >  	unsigned long flags;
> >  
> > -	if (dma_mapping_error(ref->dev, ref->dev_addr)) {
> > +	if (unlikely(has_mapping_error(ref->dev, ref->dev_addr))) {
> >  		err_printk(ref->dev, NULL, "DMA-API: device driver tries "
> >  			   "to free an invalid DMA memory address\n");
> >  		return;
> > @@ -910,6 +939,15 @@ static void check_unmap(struct dma_debug_entry *ref)
> >  			   dir2name[ref->direction]);
> >  	}
> >  
> > +	if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
> > +		err_printk(ref->dev, entry,
> > +			   "DMA-API: device driver failed to check map error"
> > +			   "[device address=0x%016llx] [size=%llu bytes] "
> > +			   "[mapped as %s]",
> > +			   ref->dev_addr, ref->size,
> > +			   type2name[entry->type]);
> > +	}
> > +
> >  	hash_bucket_del(entry);
> >  	dma_entry_free(entry);
> >  
> > @@ -1017,7 +1055,7 @@ 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(has_mapping_error(dev, dma_addr)))
> >  		return;
> >  
> >  	entry = dma_entry_alloc();
> > @@ -1030,6 +1068,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
> >  	entry->dev_addr  = dma_addr;
> >  	entry->size      = size;
> >  	entry->direction = direction;
> > +	entry->map_err_type = MAP_ERR_NOT_CHECKED;
> >  
> >  	if (map_single)
> >  		entry->type = dma_debug_single;
> > @@ -1045,6 +1084,30 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
> >  }
> >  EXPORT_SYMBOL(debug_dma_map_page);
> >  
> > +void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
> > +{
> > +	struct dma_debug_entry ref;
> > +	struct dma_debug_entry *entry;
> > +	struct hash_bucket *bucket;
> > +	unsigned long flags;
> > +
> > +	if (unlikely(global_disable))
> > +		return;
> > +
> > +	ref.dev = dev;
> > +	ref.dev_addr = dma_addr;
> > +	bucket = get_hash_bucket(&ref, &flags);
> > +	entry = bucket_find_exact(bucket, &ref);
> > +
> > +	if (!entry)
> > +		goto out;
> > +
> > +	entry->map_err_type = MAP_ERR_CHECKED;
> > +out:
> > +	put_hash_bucket(bucket, &flags);
> > +}
> > +EXPORT_SYMBOL(debug_dma_mapping_error);
> > +
> >  void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
> >  			  size_t size, int direction, bool map_single)
> >  {
> > -- 
> > 1.7.9.5
> > 
> > 

Re: [PATCH v5] dma-debug: New interfaces to debug dma mapping errors

[Andrew Morton]

On Mon, 08 Oct 2012 11:08:06 -0600
Shuah Khan <shuah.khan@hp.com> wrote:

> Add dma-debug interface debug_dma_mapping_error() to debug drivers that fail
> to check dma mapping errors on addresses returned by dma_map_single() and
> dma_map_page() interfaces. This interface clears a flag set by
> debug_dma_map_page() to indicate that dma_mapping_error() has been called by
> the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
> this flag is still set, prints warning message that includes call trace that
> leads up to the unmap. This interface can be called from dma_mapping_error()
> routines to enable dma mapping error check debugging.
> 
> Tested: Intel iommu and swiotlb (iommu=soft) on x86-64 with
>         CONFIG_DMA_API_DEBUG enabled and disabled.
> 
> Signed-off-by: Shuah Khan <shuah.khan@hp.com>
> ---
>  Documentation/DMA-API.txt          |   12 ++++++
>  arch/x86/include/asm/dma-mapping.h |    1 +
>  include/linux/dma-debug.h          |    7 ++++
>  lib/dma-debug.c                    |   71 ++++++++++++++++++++++++++++++++++--

Third time lucky ... we still haven't fixed Documentation/DMA-API-HOWTO.txt!

Please, go through it and update it to show people how to correctly use
these APIs.

Re: [PATCH v5] dma-debug: New interfaces to debug dma mapping errors

[Shuah Khan]

On Tue, 2012-10-09 at 14:06 -0700, Andrew Morton wrote:
> On Mon, 08 Oct 2012 11:08:06 -0600
> Shuah Khan <shuah.khan@hp.com> wrote:
> 
> > Add dma-debug interface debug_dma_mapping_error() to debug drivers that fail
> > to check dma mapping errors on addresses returned by dma_map_single() and
> > dma_map_page() interfaces. This interface clears a flag set by
> > debug_dma_map_page() to indicate that dma_mapping_error() has been called by
> > the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
> > this flag is still set, prints warning message that includes call trace that
> > leads up to the unmap. This interface can be called from dma_mapping_error()
> > routines to enable dma mapping error check debugging.
> > 
> > Tested: Intel iommu and swiotlb (iommu=soft) on x86-64 with
> >         CONFIG_DMA_API_DEBUG enabled and disabled.
> > 
> > Signed-off-by: Shuah Khan <shuah.khan@hp.com>
> > ---
> >  Documentation/DMA-API.txt          |   12 ++++++
> >  arch/x86/include/asm/dma-mapping.h |    1 +
> >  include/linux/dma-debug.h          |    7 ++++
> >  lib/dma-debug.c                    |   71 ++++++++++++++++++++++++++++++++++--
> 
> Third time lucky ... we still haven't fixed Documentation/DMA-API-HOWTO.txt!
> 
> Please, go through it and update it to show people how to correctly use
> these APIs.

Yes. Still on my list. I am working on the documentation changes. I am
planning to add usage examples that include calls to dma_mapping_error()
after dma_map_[page/single] calls and programming mistakes to watch out
for such as missing unmaps from  error legs etc.

-- Shuah

Re: [PATCH v5] dma-debug: New interfaces to debug dma mapping errors

[Joerg Roedel]

On Mon, Oct 08, 2012 at 11:08:06AM -0600, Shuah Khan wrote:
> Add dma-debug interface debug_dma_mapping_error() to debug drivers that fail
> to check dma mapping errors on addresses returned by dma_map_single() and
> dma_map_page() interfaces. This interface clears a flag set by
> debug_dma_map_page() to indicate that dma_mapping_error() has been called by
> the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
> this flag is still set, prints warning message that includes call trace that
> leads up to the unmap. This interface can be called from dma_mapping_error()
> routines to enable dma mapping error check debugging.
> 
> Tested: Intel iommu and swiotlb (iommu=soft) on x86-64 with
>         CONFIG_DMA_API_DEBUG enabled and disabled.
> 
> Signed-off-by: Shuah Khan <shuah.khan@hp.com>

Applied, thanks.

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