From: Alison Schofield <alison.schofield@intel.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-cxl@vger.kernel.org
Subject: Re: [PATCH] cxl/port: Fix missing target list lock
Date: Fri, 22 Dec 2023 14:03:20 -0800 [thread overview]
Message-ID: <ZYYHqFmthxW8Gazu@aschofie-mobl2> (raw)
In-Reply-To: <170322553909.110939.1669280651596703652.stgit@dwillia2-xfh.jf.intel.com>
On Thu, Dec 21, 2023 at 10:12:19PM -0800, Dan Williams wrote:
> cxl_port_setup_targets() modifies the ->targets[] array of a switch
> decoder. target_list_show() expects to be able to emit a coherent
> snapshot of that array by holding by holding ->target_lock. The
> target_lock is held for write during initialization of the ->targets[]
> array, but it is not held for write during cxl_port_setup_targets().
>
> The ->target_lock() predates the introduction of @cxl_region_rwsem. That
> semaphore protects changes to host-physical-address (HPA) decode which
> is precisely what writes to a switch decoder's target list affects.
>
> Replace ->target_lock with @cxl_region_rwsem.
>
> Now the side-effect of snapshotting a unstable view of a decoder's
> target list is likely benign so the Fixes: tag is presumptive.
>
> Fixes: 27b3f8d13830 ("cxl/region: Program target lists")
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
prev parent reply other threads:[~2023-12-22 22:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-22 6:12 [PATCH] cxl/port: Fix missing target list lock Dan Williams
2023-12-22 15:58 ` Dave Jiang
2023-12-22 22:03 ` Alison Schofield [this message]
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