Commit 69f4eb9f authored Jun 06, 2018 by Keith Busch Committed by Jens Axboe Jun 08, 2018

nvme-pci: make CMB SQ mod-param read-only



A controller reset after a run time change of the CMB module parameter
breaks the driver. An 'on -> off' will have the driver use NULL for the
host memory queue, and 'off -> on' will use mismatched queue depth between
the device and the host.

We could fix both, but there isn't really a good reason to change this
at run time anyway, compared to at module load time, so this patch makes
parameter read-only after after modprobe.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 1d39e692

drivers/nvme/host/pci.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -42,7 +42,7 @@ static int use_threaded_interrupts;
		module_param(use_threaded_interrupts, int, 0);

		static bool use_cmb_sqes = true;
		module_param(use_cmb_sqes, bool, 0644);
		module_param(use_cmb_sqes, bool, 0444);
		MODULE_PARM_DESC(use_cmb_sqes, "use controller's memory buffer for I/O SQes");

		static unsigned int max_host_mem_size_mb = 128;

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