The commit c3b1a35 "debugfs: make sure that debugfs_create_file() gets
used only for regulars" doesn't allow to use debugfs_create_file() for
creating directory, and the current debugfs_create_dir() cannot take
the private data from caller. There are some cases that we want to pass some
client data to dir, especially when dir is nested deeply. We can work
around to pass all necessary data with some invented data structure to
the end files, but if directory itself had private data, we could
avoid to introduce new structures just to pass data to end files.
For example, tegra iommu(smmu) case, debugfs structure could be as
below.
sys/
└── kernel
└── debug
├── smmu.0
│ ├── mc
│ │ ├── ptc
│ │ └── tlb
│ └── mc0
│ ├── ptc
│ └── tlb
└── smmu.1
├── mc
│ ├── ptc
│ └── tlb
├── mc0
│ ├── ptc
│ └── tlb
└── mc1
├── ptc
└── tlb
The end files, {ptc,tlb} depend on which mc? to belong to, and
which smmu.? to belong to. The parent data can be accessed from those
end files if necessary.
dent = d_find_alias(s->private);
cache = (int)dent->d_inode->i_private;
mc = (int)dent->d_parent->d_inode->i_private;
smmu = dent->d_parent->d_parent->d_inode->i_private;
The original tegra smmu debugfs patch is:
http://lists.linuxfoundation.org/pipermail/iommu/2012-August/004507.html
Hiroshi Doyu (2):
debugfs: Allow debugfs_create_dir() to take data
iommu/tegra: smmu: Use __debugfs_create_dir
drivers/iommu/tegra-smmu.c | 4 +---
fs/debugfs/inode.c | 7 ++++---
include/linux/debugfs.h | 9 ++++++++-
3 files changed, 13 insertions(+), 7 deletions(-)
--
1.7.5.4
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