On Sun, 3 Nov 2019 at 16:27, evan chime wrote: > > On Sun, 3 Nov 2019 at 16:18, Julia Lawall wrote: > >> >> >> On Sun, 3 Nov 2019, Evan Chime wrote: >> >> > Include outreachy mailing list in "cc" list. No change >> > >> > Evan Chime (3): >> > Staging: media: omap4iss: Add comment to memory barrier >> > Staging: media: omap4iss: Add comment to memory barrier >> > Staging: media: omap4iss: Add comment to memory barrier >> >> Each patch should have a different subject. If you end up with patches >> with the same subject, you should make the subjects more specific or merge >> them. >> >> In this case, though, I think that this is an issue that only someone with >> a deep knowledge of the code could really address. The question is not >> what a memory barrier does, but why one is needed at a particular place in >> the code. >> >> julia > > > Thanks for the feedback Julia > > Kind Regards > Evan > Please I have studied the function. From what I understand, the function checks if ISS submodule needs to wait for next interrupt. If yes, makes the caller to sleep while waiting for such event. The atomic_set(stopping, 1) indicates whether the submodule needs to wait, where stopping is the flag, and atomic_set(stopping, 0) indicates no need to wait According to the comment before the first atomic_set() call and the smp_wmb() call that follows which says: /* Atomic set() doesn’t include memory barrier on ARM platform for SMP scenario. We’ll call it here to avoid race conditions */, the smp_wmb() call is I think, to avoid reordering of the atomic_set() operation So can I use one of the following, as the comment A) prevent reordering of atomic_set() B) sync module with it’s idle state(from the comment that introduced the function) C) ensures *stopping is persistent D) none of the above :) > > >> >> > >> > drivers/staging/media/omap4iss/iss.c | 6 +++--- >> > 1 file changed, 3 insertions(+), 3 deletions(-) >> > >> > -- >> > 2.17.1 >> > >> > -- >> > You received this message because you are subscribed to the Google >> Groups "outreachy-kernel" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an email to outreachy-kernel+unsubscribe@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/outreachy-kernel/cover.1572797322.git.chime.evan.dri.devel%40gmail.com >> . >> > >> >> -- >> You received this message because you are subscribed to the Google Groups >> "outreachy-kernel" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to outreachy-kernel+unsubscribe@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/outreachy-kernel/alpine.DEB.2.21.1911031716390.2557%40hadrien >> . >> >