From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [alsa-devel] [PATCH] ASoC: tegra: Use flat regcache. Date: Tue, 18 Mar 2014 07:46:09 +0100 Message-ID: References: <1395115139-22243-1-git-send-email-dgreid@chromium.org> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: <1395115139-22243-1-git-send-email-dgreid-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dylan Reid Cc: alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, abrestic-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org List-Id: alsa-devel@alsa-project.org 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 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);