From: Dan Williams Date: Wed, 23 Oct 2024 01:43:32 +0000 (-0700) Subject: cxl/port: Fix cxl_bus_rescan() vs bus_rescan_devices() X-Git-Tag: v6.12~87^2~4 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3d6ebf16438de5d712030fefbb4182b46373d677;p=platform%2Fkernel%2Flinux-amlogic.git 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 Tested-by: Gregory Price Reviewed-by: Jonathan Cameron Reviewed-by: Ira Weiny Link: https://patch.msgid.link/172964781104.81806.4277549800082443769.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Ira Weiny --- 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)