Since there is no protection for vd, a kernel panic will be
triggered here in exceptional cases.
You can refer to the processing of axi_chan_block_xfer_complete function
The triggered kernel panic is as follows:
[ 67.848444] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000060
[ 67.848447] Mem abort info:
[ 67.848449] ESR = 0x96000004
[ 67.848451] EC = 0x25: DABT (current EL), IL = 32 bits
[ 67.848454] SET = 0, FnV = 0
[ 67.848456] EA = 0, S1PTW = 0
[ 67.848458] Data abort info:
[ 67.848460] ISV = 0, ISS = 0x00000004
[ 67.848462] CM = 0, WnR = 0
[ 67.848465] user pgtable: 4k pages, 48-bit VAs, pgdp=00000800c4c0b000
[ 67.848468] [0000000000000060] pgd=0000000000000000, p4d=0000000000000000
[ 67.848472] Internal error: Oops: 96000004 [#1] SMP
[ 67.848475] Modules linked in: dmatest
[ 67.848479] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.10.100-emu_x2rc+ #11
[ 67.848483] pstate: 62000085 (nZCv daIf -PAN -UAO +TCO BTYPE=--)
[ 67.848487] pc : axi_chan_handle_err+0xc4/0x230
[ 67.848491] lr : axi_chan_handle_err+0x30/0x230
[ 67.848493] sp : ffff0803fe55ae50
[ 67.848495] x29: ffff0803fe55ae50 x28: ffff800011212200
[ 67.848500] x27: ffff0800c42c0080 x26: ffff0800c097c080
[ 67.848504] x25: ffff800010d33880 x24: ffff80001139d850
[ 67.848508] x23: ffff0800c097c168 x22: 0000000000000000
[ 67.848512] x21: 0000000000000080 x20: 0000000000002000
[ 67.848517] x19: ffff0800c097c080 x18: 0000000000000000
[ 67.848521] x17: 0000000000000000 x16: 0000000000000000
[ 67.848525] x15: 0000000000000000 x14: 0000000000000000
[ 67.848529] x13: 0000000000000000 x12: 0000000000000040
[ 67.848533] x11: ffff0800c0400248 x10: ffff0800c040024a
[ 67.848538] x9 : ffff800010576cd4 x8 : ffff0800c0400270
[ 67.848542] x7 : 0000000000000000 x6 : ffff0800c04003e0
[ 67.848546] x5 : ffff0800c0400248 x4 : ffff0800c4294480
[ 67.848550] x3 : dead000000000100 x2 : dead000000000122
[ 67.848555] x1 : 0000000000000100 x0 : ffff0800c097c168
[ 67.848559] Call trace:
[ 67.848562] axi_chan_handle_err+0xc4/0x230
[ 67.848566] dw_axi_dma_interrupt+0xf4/0x590
[ 67.848569] __handle_irq_event_percpu+0x60/0x220
[ 67.848573] handle_irq_event+0x64/0x120
[ 67.848576] handle_fasteoi_irq+0xc4/0x220
[ 67.848580] __handle_domain_irq+0x80/0xe0
[ 67.848583] gic_handle_irq+0xc0/0x138
[ 67.848585] el1_irq+0xc8/0x180
[ 67.848588] arch_cpu_idle+0x14/0x2c
[ 67.848591] default_idle_call+0x40/0x16c
[ 67.848594] do_idle+0x1f0/0x250
[ 67.848597] cpu_startup_entry+0x2c/0x60
[ 67.848600] rest_init+0xc0/0xcc
[ 67.848603] arch_call_rest_init+0x14/0x1c
[ 67.848606] start_kernel+0x4cc/0x500
[ 67.848610] Code: eb0002ff 9a9f12d6 f2fbd5a2 f2fbd5a3 (a94602c1)
[ 67.848613] ---[ end trace 585a97036f88203a ]---
Signed-off-by: Shawn.Shao <shawn.shao@xxxxxxxxxxxxxxx>
---
drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
index a183d93bd..bf85aa097 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -1018,6 +1018,11 @@ static noinline void axi_chan_handle_err(struct axi_dma_chan *chan, u32 status)
/* The bad descriptor currently is in the head of vc list */
vd = vchan_next_desc(&chan->vc);
+ if (!vd) {
+ dev_err(chan2dev(chan), "BUG: %s, IRQ with no descriptors\n",
+ axi_chan_name(chan));
+ goto out;
+ }
/* Remove the completed descriptor from issued list */
list_del(&vd->node);
@@ -1032,6 +1037,7 @@ static noinline void axi_chan_handle_err(struct axi_dma_chan *chan, u32 status)
/* Try to restart the controller */
axi_chan_start_first_queued(chan);
+out:
spin_unlock_irqrestore(&chan->vc.lock, flags);
}
--
2.25.1
