With per channel stats called on thread A,
spdk_bdev_for_each_channel calls
spdk_for_each_channel which immediately sends
a message to thread B.
If thread B has no workload, it may execute the
message relatively fast trying to write stats to
json_write_ctx.
As result, we may have 2 scenarious:
1. json_write_ctx is still not initialized on
thread A, so thread B dereferences a NULL pointer.
1. json_write_ctx is initialized but thread A writes
response header while thread B writes stats - it leads
to corrupted json response.
To fix this race condition, initialize json_write_ctx
before iterating bdevs/channels
Signed-off-by: Shuhei Matsumoto <smatsumoto@nvidia.com>
Signed-off-by: Alexey Marchuk <alexeymar@nvidia.com>
Reported-by: Or Gerlitz <ogerlitz@nvidia.com>
Change-Id: I5dae37f1f527437528fc8a8e9c6066f69687dec9
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16366
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
139940d6c1