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

Shuah Khan
2012-10-09T17:26:43Z

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
> >
> >