Commit 69f4eb9f authored by Keith Busch's avatar Keith Busch Committed by Jens Axboe

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's avatarKeith Busch <>
Reviewed-by: Sagi Grimberg's avatarSagi Grimberg <>
Reviewed-by: default avatarJohannes Thumshirn <>
Signed-off-by: default avatarChristoph Hellwig <>
Signed-off-by: default avatarJens Axboe <>
parent 1d39e692
......@@ -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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