| Message ID | 20180920161423.13990-4-wsa+renesas@sang-engineering.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | i2c: core: introduce master_xfer_irqless | expand |
On 2018-09-20 18:14, Wolfram Sang wrote: > If I2C transfers are executed in atomic contexts, trylock is used > instead of lock. This behaviour was missing for SMBUS, although a lot of > transfers are of SMBUS type, either emulated or direct. So, factor out > the locking routine into a helper and use it for I2C and SMBUS. > > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Is it ok with static analyzers to "hide" the locking in helpers like this? Will it not be harder for them to "see" what's going on? But I don't think we have any annotations anyway, so... Acked-by: Peter Rosin <peda@axentia.se> > --- > drivers/i2c/i2c-core-base.c | 11 +++-------- > drivers/i2c/i2c-core-smbus.c | 7 ++++++- > drivers/i2c/i2c-core.h | 12 ++++++++++++ > 3 files changed, 21 insertions(+), 9 deletions(-) > > diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c > index 799776c6d421..904b4d2ebefa 100644 > --- a/drivers/i2c/i2c-core-base.c > +++ b/drivers/i2c/i2c-core-base.c > @@ -1943,14 +1943,9 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) > * one (discarding status on the second message) or errno > * (discarding status on the first one). > */ > - if (in_atomic() || irqs_disabled()) { > - ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT); > - if (!ret) > - /* I2C activity is ongoing. */ > - return -EAGAIN; > - } else { > - i2c_lock_bus(adap, I2C_LOCK_SEGMENT); > - } > + ret = __i2c_lock_bus_helper(adap); > + if (ret) > + return ret; > > ret = __i2c_transfer(adap, msgs, num); > i2c_unlock_bus(adap, I2C_LOCK_SEGMENT); > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c > index 9cd66cabb84f..dbb46edb8e02 100644 > --- a/drivers/i2c/i2c-core-smbus.c > +++ b/drivers/i2c/i2c-core-smbus.c > @@ -20,6 +20,8 @@ > #include <linux/i2c-smbus.h> > #include <linux/slab.h> > > +#include "i2c-core.h" > + > #define CREATE_TRACE_POINTS > #include <trace/events/smbus.h> > > @@ -530,7 +532,10 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, > { > s32 res; > > - i2c_lock_bus(adapter, I2C_LOCK_SEGMENT); > + res = __i2c_lock_bus_helper(adapter); > + if (res) > + return res; > + > res = __i2c_smbus_xfer(adapter, addr, flags, read_write, > command, protocol, data); > i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT); > diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h > index 37576f50fe20..6e98aa811980 100644 > --- a/drivers/i2c/i2c-core.h > +++ b/drivers/i2c/i2c-core.h > @@ -29,6 +29,18 @@ extern int __i2c_first_dynamic_bus_num; > > int i2c_check_7bit_addr_validity_strict(unsigned short addr); > > +static inline int __i2c_lock_bus_helper(struct i2c_adapter *adap) > +{ > + int ret = 0; > + > + if (in_atomic() || irqs_disabled()) > + ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT) ? 0 : -EAGAIN; > + else > + i2c_lock_bus(adap, I2C_LOCK_SEGMENT); > + > + return ret; > +} > + > #ifdef CONFIG_ACPI > const struct acpi_device_id * > i2c_acpi_match_device(const struct acpi_device_id *matches, >
On Thu, Sep 20, 2018 at 07:31:19PM +0200, Peter Rosin wrote: > On 2018-09-20 18:14, Wolfram Sang wrote: > > If I2C transfers are executed in atomic contexts, trylock is used > > instead of lock. This behaviour was missing for SMBUS, although a lot of > > transfers are of SMBUS type, either emulated or direct. So, factor out > > the locking routine into a helper and use it for I2C and SMBUS. > > > > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> > > Is it ok with static analyzers to "hide" the locking in helpers like > this? Will it not be harder for them to "see" what's going on? But I > don't think we have any annotations anyway, so... Yes, you are right. Yet, I prefer this to open coding the same twice and have the problem to keep them in sync.
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 799776c6d421..904b4d2ebefa 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -1943,14 +1943,9 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) * one (discarding status on the second message) or errno * (discarding status on the first one). */ - if (in_atomic() || irqs_disabled()) { - ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT); - if (!ret) - /* I2C activity is ongoing. */ - return -EAGAIN; - } else { - i2c_lock_bus(adap, I2C_LOCK_SEGMENT); - } + ret = __i2c_lock_bus_helper(adap); + if (ret) + return ret; ret = __i2c_transfer(adap, msgs, num); i2c_unlock_bus(adap, I2C_LOCK_SEGMENT); diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index 9cd66cabb84f..dbb46edb8e02 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -20,6 +20,8 @@ #include <linux/i2c-smbus.h> #include <linux/slab.h> +#include "i2c-core.h" + #define CREATE_TRACE_POINTS #include <trace/events/smbus.h> @@ -530,7 +532,10 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, { s32 res; - i2c_lock_bus(adapter, I2C_LOCK_SEGMENT); + res = __i2c_lock_bus_helper(adapter); + if (res) + return res; + res = __i2c_smbus_xfer(adapter, addr, flags, read_write, command, protocol, data); i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT); diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h index 37576f50fe20..6e98aa811980 100644 --- a/drivers/i2c/i2c-core.h +++ b/drivers/i2c/i2c-core.h @@ -29,6 +29,18 @@ extern int __i2c_first_dynamic_bus_num; int i2c_check_7bit_addr_validity_strict(unsigned short addr); +static inline int __i2c_lock_bus_helper(struct i2c_adapter *adap) +{ + int ret = 0; + + if (in_atomic() || irqs_disabled()) + ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT) ? 0 : -EAGAIN; + else + i2c_lock_bus(adap, I2C_LOCK_SEGMENT); + + return ret; +} + #ifdef CONFIG_ACPI const struct acpi_device_id * i2c_acpi_match_device(const struct acpi_device_id *matches,
If I2C transfers are executed in atomic contexts, trylock is used instead of lock. This behaviour was missing for SMBUS, although a lot of transfers are of SMBUS type, either emulated or direct. So, factor out the locking routine into a helper and use it for I2C and SMBUS. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> --- drivers/i2c/i2c-core-base.c | 11 +++-------- drivers/i2c/i2c-core-smbus.c | 7 ++++++- drivers/i2c/i2c-core.h | 12 ++++++++++++ 3 files changed, 21 insertions(+), 9 deletions(-)