from my point of view this patch is just shit. it trunkates the maximum
allocated memory to a certain value.
so firmware requests 800 kb memory but just gets 256kb. so out of bound
memory access is guaranteed at all.
Am 23.07.2016 um 00:43 schrieb Ben Greear:
On 06/13/2016 11:17 PM, Rajkumar Manoharan wrote:
commit b057886524be ("ath10k: do not use coherent memory for allocated
device memory chunks") replaced coherent memory allocation for memory
chunks to fix low memory platforms. Unfortunately this is causing system
freeze on x86 platform while bringing up qca99x0 device. The system
hangs while DMA mapping bigger memory chunks (689816/865444 bytes). Fix
this by limiting maximum memory chunk size to 256 KiB per request.
Cc: Felix Fietkau <nbd@xxxxxxxx>
Fixes: b057886524be ("ath10k: do not use coherent memory for
allocated device memory chunks")
Signed-off-by: Rajkumar Manoharan <rmanohar@xxxxxxxxxxxxxxxx>
---
drivers/net/wireless/ath/ath10k/wmi.c | 6 ++++++
drivers/net/wireless/ath/ath10k/wmi.h | 1 +
2 files changed, 7 insertions(+)
diff --git a/drivers/net/wireless/ath/ath10k/wmi.c
b/drivers/net/wireless/ath/ath10k/wmi.c
index 6279ab4a760e..7c15f65fe5ed 100644
--- a/drivers/net/wireless/ath/ath10k/wmi.c
+++ b/drivers/net/wireless/ath/ath10k/wmi.c
@@ -4411,6 +4411,12 @@ static int ath10k_wmi_alloc_chunk(struct
ath10k *ar, u32 req_id,
if (!pool_size)
return -EINVAL;
+ if (pool_size > WMI_MAX_MEM_CHUNK_SIZE) {
+ num_units = WMI_MAX_MEM_CHUNK_SIZE /
+ round_up(unit_len, 4);
+ pool_size = num_units * round_up(unit_len, 4);
+ }
I started testing my 9980 x86-64 system with VT/d enabled today.
With this patch in my tree, it crashes on bootup (with my firmware).
Works fine without this patch.
I don't see the exact place it is crashing in the firmware, though I
could
probably narrow it down with some effort. It is in the early startup
code,
at least, which makes debugging more difficult.
This patch works fine with a slightly newer firmware compiled for
9984. That
same firmware compiled for 9980 crashes, but I am not certain it is
the same issue
as the older 9980. It appears similar, at least.
Looks to me like there are lots of variances in how firmware and chip
revisions
deal with this particular code, so we are going to have to test on
lots of chips
and platforms to know if a 'fix' is really a fix or not.
Thanks,
Ben
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