Re: [PATCH v2 2/6] cxl/port: Fix cxl_bus_rescan() vs bus_rescan_devices()

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Tue, 22 Oct 2024 18:43:32 -0700
Dan Williams <dan.j.williams@intel.com> wrote:

> 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>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>