Messages in this thread | | | From | Robin Murphy <> | Subject | Re: [PATCH] dma-debug: add dumping facility via debugfs | Date | Wed, 16 Jan 2019 18:10:13 +0000 |
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On 16/01/2019 13:44, Corentin Labbe wrote: > While debugging a DMA mapping leak, I needed to access > debug_dma_dump_mappings() but easily from user space. > > This patch adds a /sys/kernel/debug/dma-api/dump file which contain all > current DMA mapping. > > Signed-off-by: Corentin Labbe <clabbe@baylibre.com> > --- > kernel/dma/debug.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 47 insertions(+) > > diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c > index 23cf5361bcf1..9253382f5729 100644 > --- a/kernel/dma/debug.c > +++ b/kernel/dma/debug.c > @@ -144,6 +144,7 @@ static struct dentry *num_free_entries_dent __read_mostly; > static struct dentry *min_free_entries_dent __read_mostly; > static struct dentry *nr_total_entries_dent __read_mostly; > static struct dentry *filter_dent __read_mostly; > +static struct dentry *dump_dent __read_mostly; > > /* per-driver filter related state */ > > @@ -840,6 +841,47 @@ static const struct file_operations filter_fops = { > .llseek = default_llseek, > }; > > +static int dump_read(struct seq_file *seq, void *v) > +{ > + int idx; > + > + for (idx = 0; idx < HASH_SIZE; idx++) { > + struct hash_bucket *bucket = &dma_entry_hash[idx]; > + struct dma_debug_entry *entry; > + unsigned long flags; > + > + spin_lock_irqsave(&bucket->lock, flags); > + > + list_for_each_entry(entry, &bucket->list, list) { > + seq_printf(seq, > + "%s %s %s idx %d P=%llx N=%lx D=%llx L=%llx %s %s\n", > + dev_name(entry->dev), > + dev_driver_string(entry->dev), > + type2name[entry->type], idx, > + phys_addr(entry), entry->pfn, > + entry->dev_addr, entry->size, > + dir2name[entry->direction], > + maperr2str[entry->map_err_type]); > + } > + > + spin_unlock_irqrestore(&bucket->lock, flags); > + } > + return 0; > +}
It's a shame that this is pretty much a duplication of debug_dma_dump_mappings(), but there seems no straightforward way to define one in terms of the other :/
(although given that we'd rather not have that weird external interface anyway, maybe "now you can use debugfs instead" might be justification enough for cleaning it up...)
> + > +static int dump_open(struct inode *inode, struct file *file) > +{ > + return single_open(file, dump_read, inode->i_private); > +} > + > +static const struct file_operations dump_fops = { > + .owner = THIS_MODULE, > + .open = dump_open, > + .read = seq_read, > + .llseek = seq_lseek, > + .release = single_release, > +}; > +
DEFINE_SHOW_ATTRIBUTE()?
Robin.
> static int dma_debug_fs_init(void) > { > dma_debug_dent = debugfs_create_dir("dma-api", NULL); > @@ -894,6 +936,11 @@ static int dma_debug_fs_init(void) > if (!filter_dent) > goto out_err; > > + dump_dent = debugfs_create_file("dump", 0444, > + dma_debug_dent, NULL, &dump_fops); > + if (!dump_dent) > + goto out_err; > + > return 0; > > out_err: >
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