Re: [PATCH v2] dma-debug: enhance dma_debug_device_change() to checkfor mapping errors

[Shuah Khan]

On 01/07/2014 10:22 AM, Shuah Khan wrote:
> On 01/07/2014 08:12 AM, Joerg Roedel wrote:
> > On Tue, Jan 07, 2014 at 08:00:33AM -0700, Shuah Khan wrote:
> > > This patch and a follow-on cocinelli warning fix patch are in
> > > linux-next. Would you like me to send a patch relative to the change
> > > in linux-next or cut a new patch against the latest Linus's git. I
> > > can go either way. We just have to remember to drop those two
> > > patches from linux-next.
> >
> > Please do a patch against linus.git and drop the two patches from
> > linux-next. Over which tree did they go into linux-next anyway?
>
> ok. It went through mm tree.

I have a separate routine now for scanning for entries with map error 
flag set and I also have a new err_printk() call to print the entry from 
dma_debug_device_change() right after device_dma_allocations() check and 
corresponding err_printk(). Snippet of the diff below. Only one warning 
gets printed. Looking at err_printk(): if (!show_all_errors && 
show_num_errors > 0) conditional, it appears that is the way it is 
supposed to work, unless I am missing something

One way to not miss the second warning is to just generate just a 
pr_err() for the mapping error instead of err_printk(). Leaked entries 
is a bigger problem that should really be shown and the same entry might 
not have the map error flag set. Thoughts?

 static int dma_debug_device_change(struct notifier_block *nb, unsigned 
long action, void *data)
 {
        struct device *dev = data;
@@ -758,6 +784,18 @@ static int dma_debug_device_change(struct 
notifier_block *nb, unsigned long acti
                                "[mapped with %s] [mapped as %s]\n",
                        count, entry->dev_addr, entry->size,
                        dir2name[entry->direction], 
type2name[entry->type]);
+
+               count = device_dma_map_errors(dev, &entry);
+               if (count == 0)
+                       break;
+               err_printk(dev, entry,
+                               "DMA-API: device driver failed to check 
map err"
+                               ": [count=%d]\n"
+                               "Details of an entry with map error flag 
set: "
+                               "[device address=0x%016llx] [size=%llu 
bytes] "
+                               "[mapped with %s] [mapped as %s]\n",
+                       count, entry->dev_addr, entry->size,
+                       dir2name[entry->direction], type2name[entry->type]);
                break;


--
Shuah Khan
Senior Linux Kernel Developer - Open Source Group
Samsung Research America(Silicon Valley)
shuah.kh@xxxxxxxxxxx | (970) 672-0658
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