[PATCH] dma: zynqmp_dma: Initialize descriptor list after freeing during reset

[RafaÅ Hibner]

List elements are not formally removed from list therefore
list head is not initialized during zynqmp_dma_reset.

Signed-off-by: Rafal Hibner <rafal.hibner@xxxxxxxxxxxx>

This BUG causes kernel panic when transaction is unsuccessful:
 ------------[ cut here ]------------
[   62.710730] list_add corruption. prev->next should be next (ffffffc07d308040), but was dead000000000100. (prev=ffffffc0540b40b8).
[   62.727960] WARNING: CPU: 0 PID: 1845 at /home/rafalh11/zynq_proj/zynq_platform/KERNEL/linux-xlnx/lib/list_debug.c:28 __list_add_valid+0x74/0xa0
[   62.746374] Modules linked in: secom_mx_rpmsg(O) rpmsg_char secom_mx_retune(O) ad9680(O) ad5686_spi(O) ad5686(O) ad7298(O) ltc5594(O) lmx2594(O) ad8366(O) secom_mx(O) axi_jesd204_rx(O) axi_adxcvr(O) xilinx_transceiver(O) cf_axi_adc_core(O) hmc7044(O)
[   62.768546] CPU: 0 PID: 1845 Comm: mx Tainted: G           O      4.19.0 #10
[   62.775582] Hardware name: xlnx,zynqmp (DT)
[   62.779750] pstate: 60000005 (nZCv daif -PAN -UAO)
[   62.784524] pc : __list_add_valid+0x74/0xa0
[   62.788690] lr : __list_add_valid+0x74/0xa0
[   62.792855] sp : ffffff8008003da0
[   62.796154] x29: ffffff8008003da0 x28: 0000000000000020
[   62.801457] x27: 0000000000000000 x26: dead000000000100
[   62.806760] x25: ffffffc07d308040 x24: ffffffc0540b40a0
[   62.812064] x23: ffffffc07d308018 x22: 0000000000000000
[   62.817359] x21: ffffffc07d308018 x20: ffffffc0540b40b8
[   62.822654] x19: ffffffc0540b40b8 x18: ffffffffffffffff
[   62.827957] x17: 0000000000000000 x16: 0000000000000000
[   62.833252] x15: ffffff8008f88648 x14: 3034303830336437
[   62.838546] x13: ffffff8008f88670 x12: ffffff80085d0ec0
[   62.843841] x11: ffffff8008f65018 x10: 0000000000000006
[   62.849136] x9 : 657270202e6e6f69 x8 : 3462303435306366
[   62.854431] x7 : 66666666663d7665 x6 : 00000000000001a2
[   62.859726] x5 : 0000000000000064 x4 : 0000000000000000
[   62.865020] x3 : 0000000000000000 x2 : ffffffffffffffff
[   62.870315] x1 : 0cbee765ba0ec900 x0 : 0000000000000000
[   62.875611] Call trace:
[   62.878042]  __list_add_valid+0x74/0xa0
[   62.881864]  zynqmp_dma_free_descriptor+0x48/0x100
[   62.886644]  zynqmp_dma_chan_desc_cleanup+0xb4/0xf8
[   62.891505]  zynqmp_dma_do_tasklet+0x68/0x110
[   62.895847]  tasklet_action_common.isra.3+0x7c/0x168
[   62.900801]  tasklet_action+0x24/0x30
[   62.904447]  __do_softirq+0x10c/0x200
[   62.908092]  irq_exit+0xac/0xc0
[   62.911219]  __handle_domain_irq+0x60/0xb0
[   62.915305]  gic_handle_irq+0x64/0xc0
[   62.918951]  el1_irq+0xb0/0x140
[   62.922078]  schedule_timeout+0x218/0x3a0
[   62.926077]  wait_for_common+0x170/0x268
[   62.929983]  wait_for_completion_timeout+0x10/0x18
[   62.934761]  ioctl+0x64/0x270 [secom_mx_retune]
[   62.939281]  do_vfs_ioctl+0xb8/0x900
[   62.942838]  ksys_ioctl+0x44/0x90
[   62.946137]  __arm64_sys_ioctl+0x1c/0x28
[   62.950044]  el0_svc_common+0x60/0xe8
[   62.953689]  el0_svc_handler+0x6c/0x88
[   62.957421]  el0_svc+0x8/0xc
[   62.960284] ---[ end trace 91b4fdfe685446c4 ]---
[   62.964934] ------------[ cut here ]------------

---
 drivers/dma/xilinx/zynqmp_dma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma/xilinx/zynqmp_dma.c b/drivers/dma/xilinx/zynqmp_dma.c
index 931e41a72..a2b0be07e 100644
--- a/drivers/dma/xilinx/zynqmp_dma.c
+++ b/drivers/dma/xilinx/zynqmp_dma.c
@@ -453,6 +453,7 @@ static void zynqmp_dma_free_desc_list(struct zynqmp_dma_chan *chan,
 
 	list_for_each_entry_safe(desc, next, list, node)
 		zynqmp_dma_free_descriptor(chan, desc);
+	INIT_LIST_HEAD(list);
 }
 
 /**
-- 
2.20.1