LSI Adapters using the megaraid_sas driver may hang during boot or an adapter reset

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux (RHEL) 6.0-6.5

Issue

  • In very limited cases, a system configured to boot through an LSI SAS adapter may hang on boot; it may also hang during an adapter reset command.
  • This latent bug, discovered during Red Hat partner testing on an LSI SAS 9285CV-8e adapter, can also occur on other cards using the megaraid_sas driver.

Resolution

  • Since the timing window for this bug is very small, rebooting the system should result in a successful boot.
  • In the case of a hang during an adapter reset command, module unload/load should resolve the issue.

RHEL 6.5

  • The issue is fixed in kernel-2.6.32-431.17.1 and later

RHEL 6.4 EUS

Root Cause

This bug which has been in the code for a long time is caused by the driver reading a hw state twice (the value is then stored in two different variables). The driver code expects the values to be the same and when it is not, the reset function may timeout. The fix reads the hw state just once (in a loop).

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