On Sun, Feb 19, 2023 at 12:11 PM Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote: > > On Sun, Feb 19, 2023 at 11:48 AM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > > > On Mon, Feb 13, 2023 at 01:55:06AM +0000, Joel Fernandes (Google) wrote: [...] > > + A: idx1 = srcu_read_lock(&s); > > + B: srcu_read_unlock(&s, idx1); > > + C: idx2 = srcu_read_lock(&s); > > + D: srcu_read_unlock(&s, idx2); > > + > > +it would appear that B was a store to a temporary variable (i.e., s) > > +and C was a load from that variable, thereby allowing carry-srcu-data > > +to extend a data dependency from A to D and giving the impression > > +that D was the srcu-unlock event matching A's srcu-lock. > > Even though it may be redundant: would it be possible to also mention > (after this paragraph) that this case forms an undesirable "->rf" link > between B and C, which then causes us to link A and D as a result? > > A[srcu-lock] ->data B[once] ->rf C[once] ->data D[srcu-unlock]. Apologies, I meant here, care must be taken to avoid: A[srcu-lock] ->data B[srcu-unlock] ->rf C[srcu-lock] ->data D[srcu-unlock]. Thanks, - Joel
