Hi Eugeniu,
Yeouch. Looks like I really missed a trick there!
We should probably update the $SUBJECT to match what is performed in the patch, which is perhaps more like:
"media: vsp1: dl: Store VSP reference when creating cmd pools"
On 23/05/2020 09:13, Eugeniu Rosca wrote:
And then we can explain here:
In commit f3b98e3c4d2e16 ("media: vsp1: Provide support for extended command pools"), the vsp pointer used for referencing the VSP1 device structure from a command pool during vsp1_dl_ext_cmd_pool_destroy() was not populated.
Correctly assign the pointer to prevent the following null-pointer-dereference when removing the device:
v4.19 commit f3b98e3c4d2e16 ("media: vsp1: Provide support for extended command pools") introduced below issue [*], consistently reproduced.
In order to fix it, inspire from the sibling/predecessor v4.18-rc1 commit 5de0473982aab2 ("media: vsp1: Provide a body pool"), which saves the vsp1 instance address in vsp1_dl_body_pool_create().
[*] h3ulcb-kf #> echo fea28000.vsp > /sys/bus/platform/devices/fea28000.vsp/driver/unbind Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028 Mem abort info: ESR = 0x96000006 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000006 CM = 0, WnR = 0 user pgtable: 4k pages, 48-bit VAs, pgdp=00000007318be000 [0000000000000028] pgd=00000007333a1003, pud=00000007333a6003, pmd=0000000000000000 Internal error: Oops: 96000006 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 486 Comm: sh Not tainted 5.7.0-rc6-arm64-renesas-00118-ge644645abf47 #185 Hardware name: Renesas H3ULCB Kingfisher board based on r8a77951 (DT) pstate: 40000005 (nZcv daif -PAN -UAO) pc : vsp1_dlm_destroy+0xe4/0x11c lr : vsp1_dlm_destroy+0xc8/0x11c sp : ffff800012963b60 x29: ffff800012963b60 x28: ffff0006f83fc440 x27: 0000000000000000 x26: ffff0006f5e13e80 x25: ffff0006f5e13ed0 x24: ffff0006f5e13ed0 x23: ffff0006f5e13ed0 x22: dead000000000122 x21: ffff0006f5e3a080 x20: ffff0006f5df2938 x19: ffff0006f5df2980 x18: 0000000000000003 x17: 0000000000000000 x16: 0000000000000016 x15: 0000000000000003 x14: 00000000000393c0 x13: ffff800011a5ec18 x12: ffff800011d8d000 x11: ffff0006f83fcc68 x10: ffff800011a53d70 x9 : ffff8000111f3000 x8 : 0000000000000000 x7 : 0000000000210d00 x6 : 0000000000000000 x5 : ffff800010872e60 x4 : 0000000000000004 x3 : 0000000078068000 x2 : ffff800012781000 x1 : 0000000000002c00 x0 : 0000000000000000 Call trace: vsp1_dlm_destroy+0xe4/0x11c vsp1_wpf_destroy+0x10/0x20 vsp1_entity_destroy+0x24/0x4c vsp1_destroy_entities+0x54/0x130 vsp1_remove+0x1c/0x40 platform_drv_remove+0x28/0x50 __device_release_driver+0x178/0x220 device_driver_detach+0x44/0xc0 unbind_store+0xe0/0x104 drv_attr_store+0x20/0x30 sysfs_kf_write+0x48/0x70 kernfs_fop_write+0x148/0x230 __vfs_write+0x18/0x40 vfs_write+0xdc/0x1c4 ksys_write+0x68/0xf0 __arm64_sys_write+0x18/0x20 el0_svc_common.constprop.0+0x70/0x170 do_el0_svc+0x20/0x80 el0_sync_handler+0x134/0x1b0 el0_sync+0x140/0x180 Code: b40000c2 f9403a60 d2800084 a9400663 (f9401400) ---[ end trace 3875369841fb288a ]---
Fixes: f3b98e3c4d2e16 ("media: vsp1: Provide support for extended command pools") Cc: stable@vger.kernel.org # v4.19+ Signed-off-by: Eugeniu Rosca erosca@de.adit-jv.com
Reviewed-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com
How about adding a new unit test perfoming unbind/rebind to http://git.ideasonboard.com/renesas/vsp-tests.git, to avoid such issues in future?
Yes, now I wish I had done so back at 4.19! I hope this wasn't too painful to diagnose and fix, and thank you for being so thorough in your report!
Locally, below command has been used to identify the problem:
for f in $(find /sys/bus/platform/devices/ -name "*vsp*" -o -name "*fdp*"); do \ b=$(basename $f); \ echo $b > $f/driver/unbind; \ done
I've created a test to add to vsp-tests, which I'll post next, thank you for the suggestion.
Before your patch is applied, I experience the same crash you have seen, and after your patch - I can successfully unbind/bind all of the VSP1 instances.
So I think you can have this too:
Tested-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com
drivers/media/platform/vsp1/vsp1_dl.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/media/platform/vsp1/vsp1_dl.c b/drivers/media/platform/vsp1/vsp1_dl.c index d7b43037e500..e07b135613eb 100644 --- a/drivers/media/platform/vsp1/vsp1_dl.c +++ b/drivers/media/platform/vsp1/vsp1_dl.c @@ -431,6 +431,8 @@ vsp1_dl_cmd_pool_create(struct vsp1_device *vsp1, enum vsp1_extcmd_type type, if (!pool) return NULL;
- pool->vsp1 = vsp1;
- spin_lock_init(&pool->lock); INIT_LIST_HEAD(&pool->free);