This patch fixes races caused by unprotected ACPI IPMI transfers.
We can see that the following crashes may occur:
1. There is no tx_msg_lock held for iterating tx_msg_list in
ipmi_flush_tx_msg() while it may be unlinked on failure in
parallel in acpi_ipmi_space_handler() under tx_msg_lock.
2. There is no lock held for freeing tx_msg in acpi_ipmi_space_handler()
while it may be accessed in parallel in ipmi_flush_tx_msg() and
ipmi_msg_handler().
This patch enhances tx_msg_lock to protect all tx_msg accesses to solve
this issue. Then tx_msg_lock is always held around complete() and tx_msg
accesses.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Reviewed-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
5ac557ef49