Messages in this thread | | | From | Tejun Heo <> | Subject | [PATCHSET v2 wq/for-6.5-cleanup-ordered] workqueue: Ordered workqueue creation cleanup | Date | Mon, 8 May 2023 15:50:19 -1000 |
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Hello,
v2: Acked patches are applied to wq/for-6.5-cleanup-ordered. Some conversion patches were dropped (e.g. because they were using WQ_SYSFS and thus can't be ordered) and fixed. The final patch to remove implicit ordered promotion logic was broken and could trigger WARN spuriously. Fixed.
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 and contains the following 13 patches on top of wq/for-6.5-cleanup-ordered branch.
0001-scsi-ncr53c8xx-Use-default-max_active-for-hostdata-w.patch 0002-wifi-mwifiex-Use-default-max_active-for-workqueues.patch 0003-dm-integrity-Use-alloc_ordered_workqueue-to-create-o.patch 0004-media-amphion-Use-alloc_ordered_workqueue-to-create-.patch 0005-wifi-ath10-11-12k-Use-alloc_ordered_workqueue-to-cre.patch 0006-net-wwan-t7xx-Use-alloc_ordered_workqueue-to-create-.patch 0007-soc-qcom-qmi-Use-alloc_ordered_workqueue-to-create-o.patch 0008-btrfs-Use-alloc_ordered_workqueue-to-create-ordered-.patch 0009-net-qrtr-Use-alloc_ordered_workqueue-to-create-order.patch 0010-rxrpc-Use-alloc_ordered_workqueue-to-create-ordered-.patch 0011-crypto-octeontx2-Use-alloc_ordered_workqueue-to-crea.patch 0012-media-coda-Use-alloc_ordered_workqueue-to-create-ord.patch 0013-workqueue-Don-t-implicitly-make-UNBOUND-workqueues-w.patch
0001-0012 convert the existing users and 0013 drops the implicit ordered promotion logic from alloc_workqueue(). I'll keep an eye out for a while after merging 0022. Thankfully, these are pretty easy to grep for. The patches can also be found in the following git branch.
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git cleanup-ordered-v2
diffstat follows. Thanks.
drivers/crypto/marvell/octeontx2/otx2_cptpf_main.c | 12 ++++++------ drivers/crypto/marvell/octeontx2/otx2_cptvf_main.c | 6 +++--- drivers/md/dm-integrity.c | 4 ++-- drivers/md/dm.c | 2 +- drivers/media/platform/amphion/vpu_core.c | 2 +- drivers/media/platform/amphion/vpu_v4l2.c | 2 +- drivers/media/platform/chips-media/coda-common.c | 2 +- drivers/net/wireless/ath/ath10k/qmi.c | 3 +-- drivers/net/wireless/ath/ath11k/qmi.c | 3 +-- drivers/net/wireless/ath/ath12k/qmi.c | 3 +-- drivers/net/wireless/marvell/mwifiex/cfg80211.c | 4 ++-- drivers/net/wireless/marvell/mwifiex/main.c | 8 ++++---- drivers/net/wwan/t7xx/t7xx_hif_cldma.c | 13 +++++++------ drivers/net/wwan/t7xx/t7xx_hif_dpmaif_tx.c | 5 +++-- drivers/scsi/NCR5380.c | 2 +- drivers/soc/qcom/qmi_interface.c | 2 +- fs/btrfs/disk-io.c | 2 +- fs/btrfs/scrub.c | 6 ++++-- include/linux/workqueue.h | 4 +--- kernel/workqueue.c | 23 ++++------------------- net/qrtr/ns.c | 2 +- net/rxrpc/af_rxrpc.c | 2 +- 22 files changed, 48 insertions(+), 64 deletions(-)
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