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| author | Dan Williams <dan.j.williams@intel.com> | 2024-10-22 18:43:32 -0700 |
|---|---|---|
| committer | Ira Weiny <ira.weiny@intel.com> | 2024-10-25 16:07:03 -0500 |
| commit | 3d6ebf16438de5d712030fefbb4182b46373d677 (patch) | |
| tree | 4e8dbaf13856a7f9376d67e441e52443aa831ba6 /drivers/cxl | |
| parent | 6575b268157f37929948a8d1f3bafb3d7c055bc1 (diff) | |
| download | lwn-3d6ebf16438de5d712030fefbb4182b46373d677.tar.gz lwn-3d6ebf16438de5d712030fefbb4182b46373d677.zip | |
cxl/port: Fix cxl_bus_rescan() vs bus_rescan_devices()
It turns out since its original introduction, pre-2.6.12,
bus_rescan_devices() has skipped devices that might be in the process of
attaching or detaching from their driver. For CXL this behavior is
unwanted and expects that cxl_bus_rescan() is a probe barrier.
That behavior is simple enough to achieve with bus_for_each_dev() paired
with call to device_attach(), and it is unclear why bus_rescan_devices()
took the position of lockless consumption of dev->driver which is racy.
The "Fixes:" but no "Cc: stable" on this patch reflects that the issue
is merely by inspection since the bug that triggered the discovery of
this potential problem [1] is fixed by other means. However, a stable
backport should do no harm.
Fixes: 8dd2bc0f8e02 ("cxl/mem: Add the cxl_mem driver")
Link: http://lore.kernel.org/20241004212504.1246-1-gourry@gourry.net [1]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://patch.msgid.link/172964781104.81806.4277549800082443769.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Diffstat (limited to 'drivers/cxl')
| -rw-r--r-- | drivers/cxl/core/port.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index e666ec6a9085..af92c67bc954 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -2084,11 +2084,18 @@ static void cxl_bus_remove(struct device *dev) static struct workqueue_struct *cxl_bus_wq; -static void cxl_bus_rescan_queue(struct work_struct *w) +static int cxl_rescan_attach(struct device *dev, void *data) { - int rc = bus_rescan_devices(&cxl_bus_type); + int rc = device_attach(dev); + + dev_vdbg(dev, "rescan: %s\n", rc ? "attach" : "detached"); - pr_debug("CXL bus rescan result: %d\n", rc); + return 0; +} + +static void cxl_bus_rescan_queue(struct work_struct *w) +{ + bus_for_each_dev(&cxl_bus_type, NULL, NULL, cxl_rescan_attach); } void cxl_bus_rescan(void) |