tree 6bd2ccbda76ba1432a4ccfc94de17f84da715b5e
parent ecda11561bbb761ebe750425cae193db4e9b3560
author Andrey Pronin <apronin@chromium.org> 1526937944 -0700
committer chrome-bot <chrome-bot@chromium.org> 1527201874 -0700

tpm_lite: stub: retry in case of TPM comm error

This CL retries reads and writes from/to TPM device if an error
is returned by read()/write(), up to 3 total attempts.

This is useful case of transient TPM communication errors that go
away after a single retry. Without this CL, after such errors the
encstateful key might be regenerated and encstateful data wiped.

BRANCH=none
BUG=chromium:702724
TEST=1) normal boot still works;
     2) simulate a single error, verify that it retries.

Change-Id: I259882209df0aad66cd083729f746ea45909922b
Reviewed-on: https://chromium-review.googlesource.com/1067939
Commit-Ready: Andrey Pronin <apronin@chromium.org>
Tested-by: Andrey Pronin <apronin@chromium.org>
Reviewed-by: Andrey Pronin <apronin@chromium.org>