Messages in this thread Patch in this message |  | | From | Matthias Schiffer <> | Subject | [PATCH] regmap: do not call regmap_debugfs_init() from regmap_attach_dev() | Date | Mon, 26 Jul 2021 09:36:27 +0200 |
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regmap_debugfs_init() should never be called twice for the same regmap, as it initializes various fields of the regmap struct, including list heads and mutices. A visible symptom are messages like:
debugfs: Directory 'dummy-iomuxc-gpr@20e4000' with parent 'regmap' already present!
This happened whenever regmap_attach_dev() was called for an existing regmap. Remove the call from regmap_attach_dev() and change __regmap_init() so that regmap_debugfs_init() is called exactly once.
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com> Fixes: 9b947a13e7f6 ("regmap: use debugfs even when no device") --- drivers/base/regmap/regmap.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
As mentioned in my previous mail [1], I believe that the duplicate call to regmap_debugfs_init() is not the only issue with regmap_attach_dev().
Every single user of regmap_attach_dev() outside of __regmap_init() is using it to attach a device to a syscon regmap obtained using one of the syscon_*() functions. AIUI, syscon regmaps do not belong to a single device, so calling regmap_attach_dev() seems wrong to me. My (possibly lacking) understanding of the semantics aside, the fact that regmap_attach_dev() is setting fields on the shared regmap without any kind of locking is at least suspicious.
Maybe regmap_attach_dev() shouldn't be exported from the regmap code at all, removing all calls to the functions from drivers?
[1] https://lkml.org/lkml/2021/7/19/500
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c index fe3e38dd5324..27625a1330ac 100644 --- a/drivers/base/regmap/regmap.c +++ b/drivers/base/regmap/regmap.c @@ -630,8 +630,6 @@ int regmap_attach_dev(struct device *dev, struct regmap *map, if (ret) return ret; - regmap_debugfs_init(map); - /* Add a devres resource for dev_get_regmap() */ m = devres_alloc(dev_get_regmap_release, sizeof(*m), GFP_KERNEL); if (!m) { @@ -1192,10 +1190,10 @@ struct regmap *__regmap_init(struct device *dev, ret = regmap_attach_dev(dev, map, config); if (ret != 0) goto err_regcache; - } else { - regmap_debugfs_init(map); } + regmap_debugfs_init(map); + return map; err_regcache: -- 2.17.1
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