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Use of rollback RCU with read-side modifications to RCU-protected data structures

  • US 8,176,489 B2
  • Filed: 12/09/2004
  • Issued: 05/08/2012
  • Est. Priority Date: 12/09/2004
  • Status: Active Grant
First Claim
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1. A program storage device, comprising:

  • program instructions stored thereon, executable by a processing device to perform operations for performing a return/rollback process for a read copy update (RCU) read-side critical section that references an RCU protected data structure, the operations comprising;

    determining a thread executing an RCU read-side critical section has been preempted, wherein the determining comprises determining that the thread is in an extended quiescent state;

    an exception handler checking a user-level state of the thread to determine whether the thread holds a lock before resuming the thread, wherein the lock for a resource is acquired in the critical section of the thread; and

    rolling back the thread to a beginning of the RCU read-side critical section of the thread when the user-level state indicates restart in absence of the lock held by the thread, else when the user-level state indicates the thread holds the lock, returning to a point of preemption, resuming execution and suspending checking of the user-level state for the lock.

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