On Mon, Nov 16, 2015 at 02:42:04PM +0100, Lars-Peter Clausen wrote:
> Prior to commit e6c9a037bc8a ("i2c: xiic: Remove the disabling of
> interrupts") IRQs where disabled when the initial __xiic_start_xfer() was
> called. After the commit the interrupt is enabled while the function is
> running, this means it is possible for the interrupt to be triggered while
> the function is still running. When this happens the internal data
> structures get corrupted and undefined behavior can occur like the
> following crash:
>
> Internal error: Oops: 17 [#1] PREEMPT SMP ARM
> Modules linked in:
> CPU: 0 PID: 2040 Comm: i2cdetect Not tainted 4.0.0-02856-g047a308 #10956
> Hardware name: Xilinx Zynq Platform
> task: ee0c9500 ti: e99a2000 task.ti: e99a2000
> PC is at __xiic_start_xfer+0x6c4/0x7c8
> LR is at __xiic_start_xfer+0x690/0x7c8
> pc : [<c02bbffc>] lr : [<c02bbfc8>] psr: 800f0013
> sp : e99a3da8 ip : 00000000 fp : 00000000
> r10: 00000001 r9 : 600f0013 r8 : f0180000
> r7 : f0180000 r6 : c064e444 r5 : 00000017 r4 : ee031010
> r3 : 00000000 r2 : 00000000 r1 : 600f0013 r0 : 0000000f
> Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
> Control: 18c5387d Table: 29a5404a DAC: 00000015
> Process i2cdetect (pid: 2040, stack limit = 0xe99a2210)
> Stack: (0xe99a3da8 to 0xe99a4000)
> 3da0: ee031010 00000000 00000001 ee031020 ee031224 c02bc5ec
> 3dc0: ee34c604 00000000 ee0c9500 e99a3dcc e99a3dd0 e99a3dd0 e99a3dd8 c069f0e8
> 3de0: 00000000 ee031020 c064e100 ffff90bb e99a3e48 c02b6590 ee031020 00000001
> 3e00: e99a3e48 ee031020 00000000 e99a3e63 00000001 c02b6ec4 00000000 00000000
> 3e20: 00000000 c02b7320 e99a3ef0 00000000 00000000 e99e3df0 00000000 00000000
> 3e40: 00000103 2814575f 0000003e c00a0000 e99a3e85 0001003e ee0c0000 e99a3e63
> 3e60: eefd3578 c064e61c ee0c9500 c0041e04 0000056c e9a56db8 00006e5a b6f5c000
> 3e80: ee0c9548 eefd0040 00000001 eefd3540 ee0c9500 eefd39a0 c064b540 ee0c9500
> 3ea0: 00000000 ee92b000 00000000 bef4862c ee34c600 e99ecdc0 00000720 00000003
> 3ec0: e99a2000 00000000 00000000 c02b8b30 00000000 00000000 00000000 e99a3f24
> 3ee0: b6e80000 00000000 00000000 c04257e8 00000000 e99a3f24 c02b8f08 00000703
> 3f00: 00000003 c02116bc ee935300 00000000 bef4862c ee34c600 e99ecdc0 c02b91f0
> 3f20: e99ecdc0 00000720 bef4862c eeb725f8 e99ecdc0 c00c9e2c 00000003 00000003
> 3f40: ee248dc0 00000000 ee248dc8 00000002 eeb7c1a8 00000000 00000000 c00bb360
> 3f60: 00000000 00000000 00000003 ee248dc0 bef4862c e99ecdc0 e99ecdc0 00000720
> 3f80: 00000003 e99a2000 00000000 c00c9f68 00000000 00000000 b6f22000 00000036
> 3fa0: c000dfa4 c000de20 00000000 00000000 00000003 00000720 bef4862c bef4862c
> 3fc0: 00000000 00000000 b6f22000 00000036 00000000 00000000 b6f60000 00000000
> 3fe0: 00013040 bef48614 00008cab b6ecdbe6 400f0030 00000003 2f7fd821 2f7fdc21
> [<c02bbffc>] (__xiic_start_xfer) from [<c02bc5ec>] (xiic_xfer+0x94/0x168)
> [<c02bc5ec>] (xiic_xfer) from [<c02b6590>] (__i2c_transfer+0x4c/0x7c)
> [<c02b6590>] (__i2c_transfer) from [<c02b6ec4>] (i2c_transfer+0x9c/0xc4)
> [<c02b6ec4>] (i2c_transfer) from [<c02b7320>] (i2c_smbus_xfer+0x3a0/0x4ec)
> [<c02b7320>] (i2c_smbus_xfer) from [<c02b8b30>] (i2cdev_ioctl_smbus+0xb0/0x214)
> [<c02b8b30>] (i2cdev_ioctl_smbus) from [<c02b91f0>] (i2cdev_ioctl+0xa0/0x1d4)
> [<c02b91f0>] (i2cdev_ioctl) from [<c00c9e2c>] (do_vfs_ioctl+0x4b0/0x5b8)
> [<c00c9e2c>] (do_vfs_ioctl) from [<c00c9f68>] (SyS_ioctl+0x34/0x5c)
> [<c00c9f68>] (SyS_ioctl) from [<c000de20>] (ret_fast_syscall+0x0/0x34)
> Code: e283300c e5843210 eafffe64 e5943210 (e1d320b4)
>
> The issue can easily be reproduced by performing I2C access under high
> system load or IO load.
>
> To fix the issue protect the invocation to __xiic_start_xfer() form
> xiic_start_xfer() with the same lock that is used to protect the interrupt
> handler.
>
> Fixes: e6c9a037bc8a ("i2c: xiic: Remove the disabling of interrupts")
> Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Applied to for-current, thanks!
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