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.

Looks like the Tegra20 drivers have the same issue as well.

-Andrew

Signed-off-by: Dylan Reid dgreid@chromium.org

sound/soc/tegra/tegra30_ahub.c | 4 ++-- sound/soc/tegra/tegra30_i2s.c | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/soc/tegra/tegra30_ahub.c b/sound/soc/tegra/tegra30_ahub.c index d6f4c99..0db68f4 100644 --- a/sound/soc/tegra/tegra30_ahub.c +++ b/sound/soc/tegra/tegra30_ahub.c @@ -471,7 +471,7 @@ static const struct regmap_config tegra30_ahub_apbif_regmap_config = { .readable_reg = tegra30_ahub_apbif_wr_rd_reg, .volatile_reg = tegra30_ahub_apbif_volatile_reg, .precious_reg = tegra30_ahub_apbif_precious_reg,

•   .cache_type = REGCACHE_RBTREE,
  

•   .cache_type = REGCACHE_FLAT,
  

};

static bool tegra30_ahub_ahub_wr_rd_reg(struct device *dev, unsigned int reg) @@ -490,7 +490,7 @@ static const struct regmap_config tegra30_ahub_ahub_regmap_config = { .max_register = LAST_REG(AUDIO_RX), .writeable_reg = tegra30_ahub_ahub_wr_rd_reg, .readable_reg = tegra30_ahub_ahub_wr_rd_reg,

•   .cache_type = REGCACHE_RBTREE,
  

•   .cache_type = REGCACHE_FLAT,
  

};

static struct tegra30_ahub_soc_data soc_data_tegra30 = { diff --git a/sound/soc/tegra/tegra30_i2s.c b/sound/soc/tegra/tegra30_i2s.c index 49ad936..f146c41 100644 --- a/sound/soc/tegra/tegra30_i2s.c +++ b/sound/soc/tegra/tegra30_i2s.c @@ -357,7 +357,7 @@ static const struct regmap_config tegra30_i2s_regmap_config = { .writeable_reg = tegra30_i2s_wr_rd_reg, .readable_reg = tegra30_i2s_wr_rd_reg, .volatile_reg = tegra30_i2s_volatile_reg,

•   .cache_type = REGCACHE_RBTREE,
  

•   .cache_type = REGCACHE_FLAT,
  

};

static const struct tegra30_i2s_soc_data tegra30_i2s_config = {

1.8.1.3.605.g02339dd

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@chromium.org

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);