drivers: Remove explicit invocations of mmiowb()

mmiowb() is now implied by spin_unlock() on architectures that require
it, so there is no reason to call it from driver code. This patch was
generated using coccinelle:

	@mmiowb@
	@@
	- mmiowb();

and invoked as:

$ for d in drivers include/linux/qed sound; do \
spatch --include-headers --sp-file mmiowb.cocci --dir $d --in-place; done

NOTE: mmiowb() has only ever guaranteed ordering in conjunction with
spin_unlock(). However, pairing each mmiowb() removal in this patch with
the corresponding call to spin_unlock() is not at all trivial, so there
is a small chance that this change may regress any drivers incorrectly
relying on mmiowb() to order MMIO writes between CPUs using lock-free
synchronisation. If you've ended up bisecting to this commit, you can
reintroduce the mmiowb() calls using wmb() instead, which should restore
the old behaviour on all architectures other than some esoteric ia64
systems.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

2 files changed, 0 insertions, 4 deletions

diff --git a/drivers/infiniband/hw/hfi1/chip.c b/drivers/infiniband/hw/hfi1/chip.c
index 12e67a91e578..8f270459b63e 100644
--- a/drivers/infiniband/hw/hfi1/chip.c
+++ b/drivers/infiniband/hw/hfi1/chip.c
@@ -8365,7 +8365,6 @@ static inline void clear_recv_intr(struct hfi1_ctxtdata *rcd)
 	struct hfi1_devdata *dd = rcd->dd;
 	u32 addr = CCE_INT_CLEAR + (8 * rcd->ireg);
 
-	mmiowb();
 	write_csr(dd, addr, rcd->imask);
 	/* force the above write on the chip and get a value back */
 	(void)read_csr(dd, addr);
@@ -11803,12 +11802,10 @@ void update_usrhead(struct hfi1_ctxtdata *rcd, u32 hd, u32 updegr, u32 egrhd,
 			<< RCV_EGR_INDEX_HEAD_HEAD_SHIFT;
 		write_uctxt_csr(dd, ctxt, RCV_EGR_INDEX_HEAD, reg);
 	}
-	mmiowb();
 	reg = ((u64)rcv_intr_count << RCV_HDR_HEAD_COUNTER_SHIFT) |
 		(((u64)hd & RCV_HDR_HEAD_HEAD_MASK)
 			<< RCV_HDR_HEAD_HEAD_SHIFT);
 	write_uctxt_csr(dd, ctxt, RCV_HDR_HEAD, reg);
-	mmiowb();
 }
 
 u32 hdrqempty(struct hfi1_ctxtdata *rcd)
diff --git a/drivers/infiniband/hw/hfi1/pio.c b/drivers/infiniband/hw/hfi1/pio.c
index a1de566fe95e..16ba9d52e1b9 100644
--- a/drivers/infiniband/hw/hfi1/pio.c
+++ b/drivers/infiniband/hw/hfi1/pio.c
@@ -1578,7 +1578,6 @@ void hfi1_sc_wantpiobuf_intr(struct send_context *sc, u32 needint)
 		sc_del_credit_return_intr(sc);
 	trace_hfi1_wantpiointr(sc, needint, sc->credit_ctrl);
 	if (needint) {
-		mmiowb();
 		sc_return_credits(sc);
 	}
 }