On 8/7/2020, Florian Fainelli wrote: > > When i2c client unregisters, synchronize irq before setting > > iproc_i2c->slave to NULL. > > > > (1) disable_irq() > > (2) Mask event enable bits in control reg > > (3) Erase slave address (avoid further writes to rx fifo) > > (4) Flush tx and rx FIFOs > > (5) Clear pending event (interrupt) bits in status reg > > (6) enable_irq() > > (7) Set client pointer to NULL > > > > > @@ -1091,6 +1091,17 @@ static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave) > > tmp &= ~BIT(S_CFG_EN_NIC_SMB_ADDR3_SHIFT); > > iproc_i2c_wr_reg(iproc_i2c, S_CFG_SMBUS_ADDR_OFFSET, tmp); > > > > + /* flush TX/RX FIFOs */ > > + tmp = (BIT(S_FIFO_RX_FLUSH_SHIFT) | BIT(S_FIFO_TX_FLUSH_SHIFT)); > > + iproc_i2c_wr_reg(iproc_i2c, S_FIFO_CTRL_OFFSET, tmp); > > + > > + /* clear all pending slave interrupts */ > > + iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, ISR_MASK_SLAVE); > > + > > + enable_irq(iproc_i2c->irq); > > + > > + iproc_i2c->slave = NULL; > > There is nothing that checks on iproc_i2c->slave being valid within the > interrupt handler, we assume that the pointer is valid which is fin, > however non functional it may be, it may feel more natural to move the > assignment before the enable_irq()? As far as the teardown sequence ensures no more interrupts arrive after enable_irq() and they are enabled only after setting pointer during client register(); checking for NULL in ISR isn't necessary. If The teardown sequence doesn't guarantee quiescing of interrupts, setting NULL before or after enable_irq() is equally vulnerable. Dhananjay
