[LU-2650] lprocfs_register() racy, returns NULL and ERR_PTR()

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.5.0
• Affects Version/s: Lustre 2.4.0
• Severity: 3
• Assignee: John Hammond
• Reporter: John Hammond

Description

lprocfs_register() should acquire _lprocfs_lock() before searching for the entry to be created. If proc_mkdir() returns NULL then this should be changed to ERR_PTR(-ENOMEM) since most callers are only testing against IS_ERR() (if that).

IS_ERR_OR_NULL() should probably be backported if needed for use with the proc wrappers.