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SubjectRe: [PATCH 1/6] drivers/i2c: Update i2c_trace_msg static key to modern api
On Mon, Mar 26, 2018 at 02:09:24PM -0700, Davidlohr Bueso wrote:
> No changes in refcount semantics -- key init is false; replace
>
> static_key_slow_inc|dec with static_branch_inc|dec
> static_key_false with static_branch_unlikely
>
> Added a '_key' suffix to i2c_trace_msg, for better self
> documentation.
>

CCing David who wrote the original code

> Cc: Wolfram Sang <wsa@the-dreams.de>
> Cc: linux-i2c@vger.kernel.org
> Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
> ---
> drivers/i2c/i2c-core-base.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 16a3b73375a6..bfcff2a6f0a3 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -69,18 +69,18 @@ static DEFINE_IDR(i2c_adapter_idr);
>
> static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
>
> -static struct static_key i2c_trace_msg = STATIC_KEY_INIT_FALSE;
> +static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key);
> static bool is_registered;
>
> int i2c_transfer_trace_reg(void)
> {
> - static_key_slow_inc(&i2c_trace_msg);
> + static_branch_inc(&i2c_trace_msg_key);
> return 0;
> }
>
> void i2c_transfer_trace_unreg(void)
> {
> - static_key_slow_dec(&i2c_trace_msg);
> + static_branch_dec(&i2c_trace_msg_key);
> }
>
> const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
> @@ -1848,11 +1848,12 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
> return -EOPNOTSUPP;
>
> - /* i2c_trace_msg gets enabled when tracepoint i2c_transfer gets
> + /*
> + * i2c_trace_msg_key gets enabled when tracepoint i2c_transfer gets
> * enabled. This is an efficient way of keeping the for-loop from
> * being executed when not needed.
> */
> - if (static_key_false(&i2c_trace_msg)) {
> + if (static_branch_unlikely(&i2c_trace_msg_key)) {
> int i;
> for (i = 0; i < num; i++)
> if (msgs[i].flags & I2C_M_RD)
> @@ -1871,7 +1872,7 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> break;
> }
>
> - if (static_key_false(&i2c_trace_msg)) {
> + if (static_branch_unlikely(&i2c_trace_msg_key)) {
> int i;
> for (i = 0; i < ret; i++)
> if (msgs[i].flags & I2C_M_RD)
> --
> 2.13.6
>
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