On 2021-06-15 12:34, Will Deacon wrote:
On Tue, Jun 15, 2021 at 07:22:10PM +0800, Leizhen (ThunderTown) wrote:
On 2021/6/11 18:32, Will Deacon wrote:
On Wed, Jun 09, 2021 at 08:54:38PM +0800, Zhen Lei wrote:
Fixes scripts/checkpatch.pl warning:
WARNING: Possible unnecessary 'out of memory' message
Remove it can help us save a bit of memory.
Signed-off-by: Zhen Lei <thunder.leiz...@huawei.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 2ddc3cd5a7d1..fd7c55b44881 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2787,10 +2787,8 @@ static int arm_smmu_init_l1_strtab(struct
arm_smmu_device *smmu)
void *strtab = smmu->strtab_cfg.strtab;
cfg->l1_desc = devm_kzalloc(smmu->dev, size, GFP_KERNEL);
- if (!cfg->l1_desc) {
- dev_err(smmu->dev, "failed to allocate l1 stream table desc\n");
+ if (!cfg->l1_desc)
What error do you get if devm_kzalloc() fails? I'd like to make sure it's
easy to track down _which_ allocation failed in that case -- does it give
you a line number, for example?
When devm_kzalloc() fails, the OOM information is printed. No line number
information, but the
size(order) and call stack is printed. It doesn't matter which allocation
failed, the failure
is caused by insufficient system memory rather than the fault of the SMMU
driver. Therefore,
the current printing is not helpful for locating the problem of insufficient
memory. After all,
when memory allocation fails, the SMMU driver cannot work at a lower
specification.
I don't entirely agree. Another reason for the failure is because the driver
might be asking for a huge (or negative) allocation, in which case it might
be instructive to have a look at the actual caller, particularly if the
size is derived from hardware or firmware properties.
Agreed - other than deliberately-contrived situations I don't think I've
ever hit a genuine OOM, but I definitely have debugged attempts to
allocate -1 of something. If the driver-specific message actually calls
out the critical information, e.g. "failed to allocate %d stream table
entries", it gives debugging a head start since the miscalculation is
obvious, but a static message that only identifies the callsite really
only saves a quick trip to scripts/faddr2line, and personally I've never
found that particularly valuable.
Robin.
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