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| author | Heiner Kallweit <hkallweit1@gmail.com> | 2024-08-15 22:44:50 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-10-10 12:58:01 +0300 |
| commit | 316be4911f636adcbb6e0f10ca6204aca7b2c1fe (patch) | |
| tree | 71f891ea099a5f6a0fc638913c664d88a724c949 /include/linux | |
| parent | 4a2be5a72865bdd219b2d8c327b9fa03e87a4a9e (diff) | |
| download | linux-316be4911f636adcbb6e0f10ca6204aca7b2c1fe.tar.xz | |
i2c: core: Lock address during client device instantiation
[ Upstream commit 8d3cefaf659265aa82b0373a563fdb9d16a2b947 ]
Krzysztof reported an issue [0] which is caused by parallel attempts to
instantiate the same I2C client device. This can happen if driver
supports auto-detection, but certain devices are also instantiated
explicitly.
The original change isn't actually wrong, it just revealed that I2C core
isn't prepared yet to handle this scenario.
Calls to i2c_new_client_device() can be nested, therefore we can't use a
simple mutex here. Parallel instantiation of devices at different addresses
is ok, so we just have to prevent parallel instantiation at the same address.
We can use a bitmap with one bit per 7-bit I2C client address, and atomic
bit operations to set/check/clear bits.
Now a parallel attempt to instantiate a device at the same address will
result in -EBUSY being returned, avoiding the "sysfs: cannot create duplicate
filename" splash.
Note: This patch version includes small cosmetic changes to the Tested-by
version, only functional change is that address locking is supported
for slave addresses too.
[0] https://lore.kernel.org/linux-i2c/9479fe4e-eb0c-407e-84c0-bd60c15baf74@ans.pl/T/#m12706546e8e2414d8f1a0dc61c53393f731685cc
Fixes: caba40ec3531 ("eeprom: at24: Probe for DDR3 thermal sensor in the SPD case")
Cc: stable@vger.kernel.org
Tested-by: Krzysztof Piotr Oledzki <ole@ans.pl>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/i2c.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 033de64d09bb..a3166100f0cc 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -748,6 +748,9 @@ struct i2c_adapter { struct regulator *bus_regulator; struct dentry *debugfs; + + /* 7bit address space */ + DECLARE_BITMAP(addrs_in_instantiation, 1 << 7); }; #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev) |