| Message ID | 20200313120133.GA17830@syed (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4,1/3] counter: 104-quad-8: Add lock guards - generic interface | expand |
On Fri, Mar 13, 2020 at 05:31:33PM +0530, Syed Nayyar Waris wrote: > Add lock protection from race conditions in the 104-quad-8 counter > driver for differential encoder cable status changes. There is no IRQ > handling so use spin_lock calls for protection. > > Fixes: bbef69e088c3 ("counter: 104-quad-8: Support Differential Encoder Cable Status") > > Signed-off-by: Syed Nayyar Waris <syednwaris@gmail.com> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> > --- > Changes in v4: > - Shift review-comments section so that it is not saved in commit message. > - Add spin_unlock calls for deadlock avoidance. > - Few changes related to casting. > > drivers/counter/104-quad-8.c | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c > index 9dab190..c9e227f 100644 > --- a/drivers/counter/104-quad-8.c > +++ b/drivers/counter/104-quad-8.c > @@ -1151,18 +1151,26 @@ static ssize_t quad8_signal_cable_fault_read(struct counter_device *counter, > struct counter_signal *signal, > void *private, char *buf) > { > - const struct quad8_iio *const priv = counter->priv; > + struct quad8_iio *const priv = counter->priv; > const size_t channel_id = signal->id / 2; > - const bool disabled = !(priv->cable_fault_enable & BIT(channel_id)); > + bool disabled; > unsigned int status; > unsigned int fault; > > - if (disabled) > + spin_lock(&priv->lock); > + > + disabled = !(priv->cable_fault_enable & BIT(channel_id)); > + > + if (disabled) { > + spin_unlock(&priv->lock); > return -EINVAL; > + } > > /* Logic 0 = cable fault */ > status = inb(priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS); > > + spin_unlock(&priv->lock); > + > /* Mask respective channel and invert logic */ > fault = !(status & BIT(channel_id)); > > @@ -1194,6 +1202,8 @@ static ssize_t quad8_signal_cable_fault_enable_write( > if (ret) > return ret; > > + spin_lock(&priv->lock); > + > if (enable) > priv->cable_fault_enable |= BIT(channel_id); > else > @@ -1204,6 +1214,8 @@ static ssize_t quad8_signal_cable_fault_enable_write( > > outb(cable_fault_enable, priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS); > > + spin_unlock(&priv->lock); > + > return len; > } > > -- > 2.7.4 >
diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c index 9dab190..c9e227f 100644 --- a/drivers/counter/104-quad-8.c +++ b/drivers/counter/104-quad-8.c @@ -1151,18 +1151,26 @@ static ssize_t quad8_signal_cable_fault_read(struct counter_device *counter, struct counter_signal *signal, void *private, char *buf) { - const struct quad8_iio *const priv = counter->priv; + struct quad8_iio *const priv = counter->priv; const size_t channel_id = signal->id / 2; - const bool disabled = !(priv->cable_fault_enable & BIT(channel_id)); + bool disabled; unsigned int status; unsigned int fault; - if (disabled) + spin_lock(&priv->lock); + + disabled = !(priv->cable_fault_enable & BIT(channel_id)); + + if (disabled) { + spin_unlock(&priv->lock); return -EINVAL; + } /* Logic 0 = cable fault */ status = inb(priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS); + spin_unlock(&priv->lock); + /* Mask respective channel and invert logic */ fault = !(status & BIT(channel_id)); @@ -1194,6 +1202,8 @@ static ssize_t quad8_signal_cable_fault_enable_write( if (ret) return ret; + spin_lock(&priv->lock); + if (enable) priv->cable_fault_enable |= BIT(channel_id); else @@ -1204,6 +1214,8 @@ static ssize_t quad8_signal_cable_fault_enable_write( outb(cable_fault_enable, priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS); + spin_unlock(&priv->lock); + return len; }
Add lock protection from race conditions in the 104-quad-8 counter driver for differential encoder cable status changes. There is no IRQ handling so use spin_lock calls for protection. Fixes: bbef69e088c3 ("counter: 104-quad-8: Support Differential Encoder Cable Status") Signed-off-by: Syed Nayyar Waris <syednwaris@gmail.com> --- Changes in v4: - Shift review-comments section so that it is not saved in commit message. - Add spin_unlock calls for deadlock avoidance. - Few changes related to casting. drivers/counter/104-quad-8.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)