At Mon, 17 Mar 2014 20:58:59 -0700,
Dylan Reid wrote:
>
> When using an rbtree cache, there can be allocations the first time a
> register is accessed. This can cause an attempt to schedule while
> atomic in the case that the regmap is using a spinlock. This could be
> fixed by either initializing all the registers or using a flat cache.
> The register maps for tegra30_ahub and tegra30_i2s are dense and don't
> save much from using a tree so convert them to flat.
>
> Signed-off-by: Dylan Reid <dgreid@xxxxxxxxxxxx>
Looking through regmap code, the fast_io lock seems broken in more
places, not only via rbtree cache access. regmap_bulk_write() calls
kmemdup() with GFP_KERNEL in the lock context. Ditto in
regmap_register_patch(), which calls krealloc() with GFP_KERNEL.
The former could be fixed by moving the lock like below. The fix for
the latter depends on whether we need to protect map->patch_regs
growth from races or not. If not, krealloc() can be moved out of the
lock.
Takashi
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 4b2ed0c9e80d..2a1d43e23f1f 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1520,12 +1520,12 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
if (reg % map->reg_stride)
return -EINVAL;
- map->lock(map->lock_arg);
/*
* Some devices don't support bulk write, for
* them we have a series of single write operations.
*/
if (!map->bus || map->use_single_rw) {
+ map->lock(map->lock_arg);
for (i = 0; i < val_count; i++) {
unsigned int ival;
@@ -1554,24 +1554,25 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
if (ret != 0)
goto out;
}
+ out:
+ map->unlock(map->lock_arg);
} else {
void *wval;
wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
if (!wval) {
- ret = -ENOMEM;
dev_err(map->dev, "Error in memory allocation\n");
- goto out;
+ return -ENOMEM;
}
+ map->lock(map->lock_arg);
for (i = 0; i < val_count * val_bytes; i += val_bytes)
map->format.parse_inplace(wval + i);
ret = _regmap_raw_write(map, reg, wval, val_bytes * val_count);
+ map->unlock(map->lock_arg);
kfree(wval);
}
-out:
- map->unlock(map->lock_arg);
return ret;
}
EXPORT_SYMBOL_GPL(regmap_bulk_write);
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