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authorNiklas Söderlund <niklas.soderlund+renesas@ragnatech.se>2017-05-16 02:09:17 +0300
committerVinod Koul <vinod.koul@intel.com>2017-05-19 12:25:23 +0300
commita1ed64efc5f68fc830fea08e96363d4459bb07a6 (patch)
treefd83bb08a3dbb44ec8043c55c65c4b15a2d22ae5 /drivers/dma/sh
parent30c45005a46bf55ba52086da5e090ec5a2f1c949 (diff)
downloadlinux-a1ed64efc5f68fc830fea08e96363d4459bb07a6.tar.xz
dmaengine: rcar-dmac: wait for ISR to finish before freeing resources
This fixes a race condition where the channel resources could be freed before the ISR had finished running resulting in a NULL pointer reference from the ISR. [ 167.148934] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 167.157051] pgd = ffff80003c641000 [ 167.160449] [00000000] *pgd=000000007c507003, *pud=000000007c4ff003, *pmd=0000000000000000 [ 167.168719] Internal error: Oops: 96000046 [#1] PREEMPT SMP [ 167.174289] Modules linked in: [ 167.177348] CPU: 3 PID: 10547 Comm: dma_ioctl Not tainted 4.11.0-rc1-00001-g8d92afddc2f6633a #73 [ 167.186131] Hardware name: Renesas Salvator-X board based on r8a7795 (DT) [ 167.192917] task: ffff80003a411a00 task.stack: ffff80003bcd4000 [ 167.198850] PC is at rcar_dmac_chan_prep_sg+0xe0/0x400 [ 167.203985] LR is at rcar_dmac_chan_prep_sg+0x48/0x400 Based of previous work by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>. Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers/dma/sh')
-rw-r--r--drivers/dma/sh/rcar-dmac.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index fb07cd5fe77b..d2cb4a0916e6 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1010,7 +1010,11 @@ static void rcar_dmac_free_chan_resources(struct dma_chan *chan)
rcar_dmac_chan_halt(rchan);
spin_unlock_irq(&rchan->lock);
- /* Now no new interrupts will occur */
+ /*
+ * Now no new interrupts will occur, but one might already be
+ * running. Wait for it to finish before freeing resources.
+ */
+ synchronize_irq(rchan->irq);
if (rchan->mid_rid >= 0) {
/* The caller is holding dma_list_mutex */