[PATCH 2/3] nvme-pci: limit maximum queue depth to 4095

[Sagi Grimberg]

We are going to use the upper 4-bits of the command_id for a generation
counter, so enforce the new queue depth upper limit.

Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
---
 drivers/nvme/host/pci.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index a29b170701fc..bc64282b2301 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -60,6 +60,7 @@ MODULE_PARM_DESC(sgl_threshold,
 		"Use SGLs when average request segment size is larger or equal to "
 		"this size. Use 0 to disable SGLs.");
 
+#define NVME_PCI_MAX_QUEUE_SIZE 4095
 static int io_queue_depth_set(const char *val, const struct kernel_param *kp);
 static const struct kernel_param_ops io_queue_depth_ops = {
 	.set = io_queue_depth_set,
@@ -68,7 +69,7 @@ static const struct kernel_param_ops io_queue_depth_ops = {
 
 static unsigned int io_queue_depth = 1024;
 module_param_cb(io_queue_depth, &io_queue_depth_ops, &io_queue_depth, 0644);
-MODULE_PARM_DESC(io_queue_depth, "set io queue depth, should >= 2");
+MODULE_PARM_DESC(io_queue_depth, "set io queue depth, should >= 2 and < 4096");
 
 static int io_queue_count_set(const char *val, const struct kernel_param *kp)
 {
@@ -161,7 +162,7 @@ static int io_queue_depth_set(const char *val, const struct kernel_param *kp)
 	u32 n;
 
 	ret = kstrtou32(val, 10, &n);
-	if (ret != 0 || n < 2)
+	if (ret != 0 || n < 2 || n > NVME_PCI_MAX_QUEUE_SIZE)
 		return -EINVAL;
 
 	return param_set_uint(val, kp);
-- 
2.27.0