On 8/10/2020 5:42 PM, Dhananjay Phadke 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
>
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000318
>
> [ 371.020421] pc : bcm_iproc_i2c_isr+0x530/0x11f0
> [ 371.025098] lr : __handle_irq_event_percpu+0x6c/0x170
> [ 371.030309] sp : ffff800010003e40
> [ 371.033727] x29: ffff800010003e40 x28: 0000000000000060
> [ 371.039206] x27: ffff800010ca9de0 x26: ffff800010f895df
> [ 371.044686] x25: ffff800010f18888 x24: ffff0008f7ff3600
> [ 371.050165] x23: 0000000000000003 x22: 0000000001600000
> [ 371.055645] x21: ffff800010f18888 x20: 0000000001600000
> [ 371.061124] x19: ffff0008f726f080 x18: 0000000000000000
> [ 371.066603] x17: 0000000000000000 x16: 0000000000000000
> [ 371.072082] x15: 0000000000000000 x14: 0000000000000000
> [ 371.077561] x13: 0000000000000000 x12: 0000000000000001
> [ 371.083040] x11: 0000000000000000 x10: 0000000000000040
> [ 371.088519] x9 : ffff800010f317c8 x8 : ffff800010f317c0
> [ 371.093999] x7 : ffff0008f805b3b0 x6 : 0000000000000000
> [ 371.099478] x5 : ffff0008f7ff36a4 x4 : ffff8008ee43d000
> [ 371.104957] x3 : 0000000000000000 x2 : ffff8000107d64c0
> [ 371.110436] x1 : 00000000c00000af x0 : 0000000000000000
>
> [ 371.115916] Call trace:
> [ 371.118439] bcm_iproc_i2c_isr+0x530/0x11f0
> [ 371.122754] __handle_irq_event_percpu+0x6c/0x170
> [ 371.127606] handle_irq_event_percpu+0x34/0x88
> [ 371.132189] handle_irq_event+0x40/0x120
> [ 371.136234] handle_fasteoi_irq+0xcc/0x1a0
> [ 371.140459] generic_handle_irq+0x24/0x38
> [ 371.144594] __handle_domain_irq+0x60/0xb8
> [ 371.148820] gic_handle_irq+0xc0/0x158
> [ 371.152687] el1_irq+0xb8/0x140
> [ 371.155927] arch_cpu_idle+0x10/0x18
> [ 371.159615] do_idle+0x204/0x290
> [ 371.162943] cpu_startup_entry+0x24/0x60
> [ 371.166990] rest_init+0xb0/0xbc
> [ 371.170322] arch_call_rest_init+0xc/0x14
> [ 371.174458] start_kernel+0x404/0x430
>
> Fixes: c245d94ed106 ("i2c: iproc: Add multi byte read-write support for slave mode")
>
> Signed-off-by: Dhananjay Phadke <dphadke@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-bcm-iproc.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
> index 8a3c98866fb7..688e92818821 100644
> --- a/drivers/i2c/busses/i2c-bcm-iproc.c
> +++ b/drivers/i2c/busses/i2c-bcm-iproc.c
> @@ -1078,7 +1078,7 @@ static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave)
> if (!iproc_i2c->slave)
> return -EINVAL;
>
> - iproc_i2c->slave = NULL;
> + disable_irq(iproc_i2c->irq);
>
> /* disable all slave interrupts */
> tmp = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
> @@ -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);
> +
> + iproc_i2c->slave = NULL;
> +
> + enable_irq(iproc_i2c->irq);
> +
> return 0;
> }
>
>
Thanks again, Dhananjay! Looks good to me.
Acked-by: Ray Jui <ray.jui@xxxxxxxxxxxx>
