* [PATCH] i2c: core: Serialize 10-bit client instantiation with mutex
@ 2025-06-14 8:37 Abd-Alrhman Masalkhi
2025-06-21 9:17 ` Abd-Alrhman Masalkhi
0 siblings, 1 reply; 2+ messages in thread
From: Abd-Alrhman Masalkhi @ 2025-06-14 8:37 UTC (permalink / raw)
To: wsa+renesas; +Cc: linux-i2c, linux-kernel, Abd-Alrhman Masalkhi
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 --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)
--
2.43.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] i2c: core: Serialize 10-bit client instantiation with mutex
2025-06-14 8:37 [PATCH] i2c: core: Serialize 10-bit client instantiation with mutex Abd-Alrhman Masalkhi
@ 2025-06-21 9:17 ` Abd-Alrhman Masalkhi
0 siblings, 0 replies; 2+ messages in thread
From: Abd-Alrhman Masalkhi @ 2025-06-21 9:17 UTC (permalink / raw)
To: abd.masalkhi; +Cc: linux-i2c, linux-kernel, wsa+renesas
Hi all,
Gentle ping.
Best regards,
Abd-Alrhman Masalkhi
On 2025/6/14 08:37, Abd-Alrhman Masalkhi wrote:
> 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 --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)
>
> --
> 2.43.0
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2025-06-21 9:18 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-06-14 8:37 [PATCH] i2c: core: Serialize 10-bit client instantiation with mutex Abd-Alrhman Masalkhi
2025-06-21 9:17 ` Abd-Alrhman Masalkhi
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).