From: Ray Jui <ray.jui@broadcom.com>
To: Dhananjay Phadke <dphadke@linux.microsoft.com>,
Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
Wolfram Sang <wsa@kernel.org>
Cc: Ray Jui <rjui@broadcom.com>, bcm-kernel-feedback-list@broadcom.com
Subject: Re: [PATCH] i2c: iproc: fix race between client unreg and isr
Date: Mon, 20 Jul 2020 10:49:06 -0700 [thread overview]
Message-ID: <116ac90c-8b49-ca89-90a4-9a28f43a7c50@broadcom.com> (raw)
In-Reply-To: <1595115599-100054-1-git-send-email-dphadke@linux.microsoft.com>
On 7/18/2020 4:39 PM, Dhananjay Phadke wrote:
> When i2c client unregisters, synchronize irq before setting
> iproc_i2c->slave 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@linux.microsoft.com>
> ---
> drivers/i2c/busses/i2c-bcm-iproc.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
> index b58224b7b..37d2a79e7 100644
> --- a/drivers/i2c/busses/i2c-bcm-iproc.c
> +++ b/drivers/i2c/busses/i2c-bcm-iproc.c
> @@ -1074,14 +1074,15 @@ static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave)
> if (!iproc_i2c->slave)
> return -EINVAL;
>
> - iproc_i2c->slave = NULL;
> -
> /* disable all slave interrupts */
> tmp = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
> tmp &= ~(IE_S_ALL_INTERRUPT_MASK <<
> IE_S_ALL_INTERRUPT_SHIFT);
> iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, tmp);
>
> + synchronize_irq(iproc_i2c->irq);
If one takes a look at the I2C slave ISR routine, there are places where
IRQ can be re-enabled in the ISR itself. What happens after we mask all
slave interrupt and when 'synchronize_irq' is called, which I suppose is
meant to wait for inflight interrupt to finish where there's a chance
the interrupt can be re-enable again? How is one supposed to deal with that?
Thanks,
Ray
> + iproc_i2c->slave = NULL;
> +
> /* Erase the slave address programmed */
> tmp = iproc_i2c_rd_reg(iproc_i2c, S_CFG_SMBUS_ADDR_OFFSET);
> tmp &= ~BIT(S_CFG_EN_NIC_SMB_ADDR3_SHIFT);
>
next prev parent reply other threads:[~2020-07-20 17:49 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-18 23:39 [PATCH] i2c: iproc: fix race between client unreg and isr Dhananjay Phadke
2020-07-19 7:59 ` Rayagonda Kokatanur
2020-07-20 17:40 ` Scott Branden
2020-07-20 17:49 ` Ray Jui [this message]
2020-07-22 10:41 ` Wolfram Sang
2020-07-22 15:51 ` Ray Jui
2020-07-22 16:55 ` Ray Jui
2020-07-23 0:58 ` Dhananjay Phadke
2020-07-25 10:18 ` Wolfram Sang
2020-07-27 4:32 ` Rayagonda Kokatanur
2020-07-27 15:42 ` Ray Jui
2020-07-27 17:38 ` Dhananjay Phadke
2020-07-27 18:13 ` Wolfram Sang
2020-07-27 20:26 ` Wolfram Sang
2020-07-27 20:43 ` Ray Jui
2020-08-05 9:17 ` Wolfram Sang
2020-08-07 16:40 ` Ray Jui
2020-08-07 17:38 ` Dhananjay Phadke
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