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i2c: core: Serialize 10-bit client instantiation with mutex

Message ID 20250614083734.3385182-1-abd.masalkhi@gmail.com
State New
Headers show
Series i2c: core: Serialize 10-bit client instantiation with mutex | expand

Commit Message

Abd-Alrhman Masalkhi June 14, 2025, 8:37 a.m. UTC 
Add a mutex to protect against race conditions when instantiating
10-bit address I2C clients. It serves the same purpose as the 7-bit
address bitmap (addrs_in_instantiation), but uses a mutex instead,
since 10-bit clients are rare and a full bitmap would unnecessarily
increase the size of struct i2c_adapter.

Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
---
 drivers/i2c/i2c-core-base.c | 8 +++++++-
 include/linux/i2c.h         | 3 +++
 2 files changed, 10 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 2ad2b1838f0f..f5f53d378fff 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -929,6 +929,9 @@  int i2c_dev_irq_from_resources(const struct resource *resources,
 static int i2c_lock_addr(struct i2c_adapter *adap, unsigned short addr,
 			 unsigned short flags)
 {
+	if (flags & I2C_CLIENT_TEN)
+		mutex_lock(&adap->addrs_10bit_lock);
+
 	if (!(flags & I2C_CLIENT_TEN) &&
 	    test_and_set_bit(addr, adap->addrs_in_instantiation))
 		return -EBUSY;
@@ -939,7 +942,9 @@  static int i2c_lock_addr(struct i2c_adapter *adap, unsigned short addr,
 static void i2c_unlock_addr(struct i2c_adapter *adap, unsigned short addr,
 			    unsigned short flags)
 {
-	if (!(flags & I2C_CLIENT_TEN))
+	if (flags & I2C_CLIENT_TEN)
+		mutex_unlock(&adap->addrs_10bit_lock);
+	else
 		clear_bit(addr, adap->addrs_in_instantiation);
 }
 
@@ -1538,6 +1543,7 @@  static int i2c_register_adapter(struct i2c_adapter *adap)
 	adap->locked_flags = 0;
 	rt_mutex_init(&adap->bus_lock);
 	rt_mutex_init(&adap->mux_lock);
+	mutex_init(&adap->addrs_10bit_lock);
 	mutex_init(&adap->userspace_clients_lock);
 	INIT_LIST_HEAD(&adap->userspace_clients);
 
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 20fd41b51d5c..1d4d0577b5b1 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -765,6 +765,9 @@  struct i2c_adapter {
 
 	/* 7bit address space */
 	DECLARE_BITMAP(addrs_in_instantiation, 1 << 7);
+
+	/* Lock for 10bit address instantiation */
+	struct mutex addrs_10bit_lock;
 };
 #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)