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| author | Dan Williams <dan.j.williams@intel.com> | 2022-01-31 15:35:18 -0800 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2022-02-08 22:57:29 -0800 |
| commit | 86c8ea0f3b32aae6d824bdc0d835b6a9361dc912 (patch) | |
| tree | 8f7c42cf62516c14facb2d8c3249c9c8ce08012b /drivers/cxl/cxl.h | |
| parent | 3c5b903955251ea464fca383a42d981e33004df6 (diff) | |
| download | lwn-86c8ea0f3b32aae6d824bdc0d835b6a9361dc912.tar.gz lwn-86c8ea0f3b32aae6d824bdc0d835b6a9361dc912.zip | |
cxl/core/port: Use dedicated lock for decoder target list
Lockdep reports:
======================================================
WARNING: possible circular locking dependency detected
5.16.0-rc1+ #142 Tainted: G OE
------------------------------------------------------
cxl/1220 is trying to acquire lock:
ffff979b85475460 (kn->active#144){++++}-{0:0}, at: __kernfs_remove+0x1ab/0x1e0
but task is already holding lock:
ffff979b87ab38e8 (&dev->lockdep_mutex#2/4){+.+.}-{3:3}, at: cxl_remove_ep+0x50c/0x5c0 [cxl_core]
...where cxl_remove_ep() is a helper that wants to delete ports while
holding a lock on the host device for that port. That sets up a lockdep
violation whereby target_list_show() can not rely holding the decoder's
device lock while walking the target_list. Switch to a dedicated seqlock
for this purpose.
Reported-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164367209095.208169.1171673319121271280.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/cxl/cxl.h')
| -rw-r--r-- | drivers/cxl/cxl.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index 6a38d2e1f3dd..e79162999088 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -185,6 +185,7 @@ enum cxl_decoder_type { * @interleave_granularity: data stride per dport * @target_type: accelerator vs expander (type2 vs type3) selector * @flags: memory type capabilities and locking + * @target_lock: coordinate coherent reads of the target list * @nr_targets: number of elements in @target * @target: active ordered target list in current decoder configuration */ @@ -199,6 +200,7 @@ struct cxl_decoder { int interleave_granularity; enum cxl_decoder_type target_type; unsigned long flags; + seqlock_t target_lock; int nr_targets; struct cxl_dport *target[]; }; |