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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=116ac90c-8b49-ca89-90a4-9a28f43a7c50@broadcom.com \
--to=ray.jui@broadcom.com \
--cc=bcm-kernel-feedback-list@broadcom.com \
--cc=dphadke@linux.microsoft.com \
--cc=linux-i2c@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rayagonda.kokatanur@broadcom.com \
--cc=rjui@broadcom.com \
--cc=wsa@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.