net: octeontx2: Use alloc_ordered_workqueue() to create ordered workqueues

BACKGROUND
==========

When multiple work items are queued to a workqueue, their execution order
doesn't match the queueing order. They may get executed in any order and
simultaneously. When fully serialized execution - one by one in the queueing
order - is needed, an ordered workqueue should be used which can be created
with alloc_ordered_workqueue().

However, alloc_ordered_workqueue() was a later addition. Before it, an
ordered workqueue could be obtained by creating an UNBOUND workqueue with
@max_active==1. This originally was an implementation side-effect which was
broken by 4c16bd327c74 ("workqueue: restore WQ_UNBOUND/max_active==1 to be
ordered"). Because there were users that depended on the ordered execution,
5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered")
made workqueue allocation path to implicitly promote UNBOUND workqueues w/
@max_active==1 to ordered workqueues.

While this has worked okay, overloading the UNBOUND allocation interface
this way creates other issues. It's difficult to tell whether a given
workqueue actually needs to be ordered and users that legitimately want a
min concurrency level wq unexpectedly gets an ordered one instead. With
planned UNBOUND workqueue updates to improve execution locality and more
prevalence of chiplet designs which can benefit from such improvements, this
isn't a state we wanna be in forever.

This patch series audits all callsites that create an UNBOUND workqueue w/
@max_active==1 and converts them to alloc_ordered_workqueue() as necessary.

WHAT TO LOOK FOR
================

The conversions are from

  alloc_workqueue(WQ_UNBOUND | flags, 1, args..)

to

  alloc_ordered_workqueue(flags, args...)

which don't cause any functional changes. If you know that fully ordered
execution is not ncessary, please let me know. I'll drop the conversion and
instead add a comment noting the fact to reduce confusion while conversion
is in progress.

If you aren't fully sure, it's completely fine to let the conversion
through. The behavior will stay exactly the same and we can always
reconsider later.

As there are follow-up workqueue core changes, I'd really appreciate if the
patch can be routed through the workqueue tree w/ your acks. Thanks.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Sunil Goutham <sgoutham@marvell.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Ratheesh Kannoth <rkannoth@marvell.com>
Cc: Srujana Challa <schalla@marvell.com>
Cc: Geetha sowjanya <gakula@marvell.com>
Cc: netdev@vger.kernel.org

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
index 9f673bda9dbdd5898e8c58b821cd8178e8c3bf55..0069e60afa3b024c656461ae84668d23091a707c 100644 (file)
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
@@ -3044,9 +3044,8 @@ static int rvu_flr_init(struct rvu *rvu)
                            cfg | BIT_ULL(22));
        }
 
-       rvu->flr_wq = alloc_workqueue("rvu_afpf_flr",
-                                     WQ_UNBOUND | WQ_HIGHPRI | WQ_MEM_RECLAIM,
-                                      1);
+       rvu->flr_wq = alloc_ordered_workqueue("rvu_afpf_flr",
+                                             WQ_HIGHPRI | WQ_MEM_RECLAIM);
        if (!rvu->flr_wq)
                return -ENOMEM;
 

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
index 18284ad751572006d41c5b724aff5f9628d741bc..74c49795dc827b2f5c6b58132eaea7c22ea82866 100644 (file)
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
@@ -271,8 +271,7 @@ static int otx2_pf_flr_init(struct otx2_nic *pf, int num_vfs)
 {
        int vf;
 
-       pf->flr_wq = alloc_workqueue("otx2_pf_flr_wq",
-                                    WQ_UNBOUND | WQ_HIGHPRI, 1);
+       pf->flr_wq = alloc_ordered_workqueue("otx2_pf_flr_wq", WQ_HIGHPRI);
        if (!pf->flr_wq)
                return -ENOMEM;
 
@@ -593,9 +592,8 @@ static int otx2_pfvf_mbox_init(struct otx2_nic *pf, int numvfs)
        if (!pf->mbox_pfvf)
                return -ENOMEM;
 
-       pf->mbox_pfvf_wq = alloc_workqueue("otx2_pfvf_mailbox",
-                                          WQ_UNBOUND | WQ_HIGHPRI |
-                                          WQ_MEM_RECLAIM, 1);
+       pf->mbox_pfvf_wq = alloc_ordered_workqueue("otx2_pfvf_mailbox",
+                                                  WQ_HIGHPRI | WQ_MEM_RECLAIM);
        if (!pf->mbox_pfvf_wq)
                return -ENOMEM;
 
@@ -1063,9 +1061,8 @@ static int otx2_pfaf_mbox_init(struct otx2_nic *pf)
        int err;
 
        mbox->pfvf = pf;
-       pf->mbox_wq = alloc_workqueue("otx2_pfaf_mailbox",
-                                     WQ_UNBOUND | WQ_HIGHPRI |
-                                     WQ_MEM_RECLAIM, 1);
+       pf->mbox_wq = alloc_ordered_workqueue("otx2_pfaf_mailbox",
+                                             WQ_HIGHPRI | WQ_MEM_RECLAIM);
        if (!pf->mbox_wq)
                return -ENOMEM;
 

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_vf.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_vf.c
index 53366dbfbf27c3a63e8bfda0531e86a2e711389c..7baed6bb3b72d1c4694ae3bb7e5ac89b9ef95b5f 100644 (file)
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_vf.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_vf.c
@@ -297,9 +297,8 @@ static int otx2vf_vfaf_mbox_init(struct otx2_nic *vf)
        int err;
 
        mbox->pfvf = vf;
-       vf->mbox_wq = alloc_workqueue("otx2_vfaf_mailbox",
-                                     WQ_UNBOUND | WQ_HIGHPRI |
-                                     WQ_MEM_RECLAIM, 1);
+       vf->mbox_wq = alloc_ordered_workqueue("otx2_vfaf_mailbox",
+                                             WQ_HIGHPRI | WQ_MEM_RECLAIM);
        if (!vf->mbox_wq)
                return -ENOMEM;