Re: [PATCH v2] taskstats: fix data-race

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static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk) { struct signal_struct *sig = tsk->signal;

• struct taskstats *stats;
  

• struct taskstats *stats_new, *stats;
  
  

• if (sig->stats || thread_group_empty(tsk))
  

•         goto ret;
  

• /* Pairs with smp_store_release() below. */
  

• stats = READ_ONCE(sig->stats);
  

This pairing suggests that the READ_ONCE() is heading an address dependency, but I fail to identify it: what is the target memory access of such a (putative) dependency?

I would assume callers of this function access *stats. So the dependency is between loading stats and accessing *stats.

AFAICT, the only caller of the function in 5.4-rc2 is taskstats_exit(), which 'casts' the return value to a boolean (so I really don't see how any address dependency could be carried over/relied upon here).

Andrea