8:04 a.m.
I will drop this patch, because I have a doubt:
Suppose the nd_region->ndr_mappings is 4, and for each nd_region->mapping[],
the value of num_flush is "0, 0, 4, 0", so the flush_data_size is "1 + 1 +
5 + 1", * sizeof(void *).
But in ndrd_get_flush_wpq() or ndrd_set_flush_wpq(), the expression is
"ndrd->flush_wpq[dimm * num + (hint & mask)]", I don't think the
memory "ndrd" allocated is enough.
Please refer call chain: nd_region_activate() --> nvdimm_map_flush() -->
ndrd_set_flush_wpq()
for (i = 0; i < nd_region->ndr_mappings; i++) {
struct nd_mapping *nd_mapping = &nd_region->mapping[i];
struct nvdimm *nvdimm = nd_mapping->nvdimm;
/* at least one null hint slot per-dimm for the "no-hint" case
*/
flush_data_size += sizeof(void *);
num_flush = min_not_zero(num_flush, nvdimm->num_flush);
if (!nvdimm->num_flush)
continue;
flush_data_size += nvdimm->num_flush * sizeof(void *);
}
ndrd = devm_kzalloc(dev, sizeof(*ndrd) + flush_data_size, GFP_KERNEL);
On 2020/8/20 10:16, Zhen Lei wrote:
According to the original code logic:
if (!nvdimm->num_flush) {
flush_data_size += sizeof(void *);
//nvdimm->num_flush is zero now, add 1) have no side effects
} else {
flush_data_size += sizeof(void *);
1) flush_data_size += nvdimm->num_flush * sizeof(void *);
}
Obviously, the above code snippet can be reduced to one statement:
flush_data_size += (nvdimm->num_flush + 1) * sizeof(void *);
No functional change.
Signed-off-by: Zhen Lei <thunder.leizhen(a)huawei.com>
---
drivers/nvdimm/region_devs.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 7cf9c7d857909ce..49be115c9189eff 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -77,11 +77,8 @@ int nd_region_activate(struct nd_region *nd_region)
}
/* at least one null hint slot per-dimm for the "no-hint" case */
- flush_data_size += sizeof(void *);
+ flush_data_size += (nvdimm->num_flush + 1) * sizeof(void *);
num_flush = min_not_zero(num_flush, nvdimm->num_flush);
- if (!nvdimm->num_flush)
- continue;
- flush_data_size += nvdimm->num_flush * sizeof(void *);
}
nvdimm_bus_unlock(&nd_region->dev);