Looking at the hctxs and cpumap is not safe without at very last a RCU
reference. It also requires the queue to be set up before starting the
device, which leads to rather awkware life time rules.
Instead rewrite ublk_ctrl_get_queue_affinity to call blk_mq_map_queues
on an on-stack blk_mq_queue_map and build the cpumask from that.
Note: given that ublk has not made it into a released kernel it might
make sense to change the ABI for this command to instead copy the
qmap.mq_map array (a nr_cpu_ids sized array of unsigned integer
values where the CPU index directly points to the queue) to userspace.
That way all the information could be transported to userspace in a
single command.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
drivers/block/ublk_drv.c | 63 ++++++++++++++++++++--------------------
1 file changed, 32 insertions(+), 31 deletions(-)
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 7d57cbecfc8a0..67c6c46b8e07e 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1245,26 +1245,16 @@ static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd)
return ret;
}
-static struct blk_mq_hw_ctx *ublk_get_hw_queue(struct ublk_device *ub,
- unsigned int index)
-{
- struct blk_mq_hw_ctx *hctx;
- unsigned long i;
-
- queue_for_each_hw_ctx(ub->ub_queue, hctx, i)
- if (hctx->queue_num == index)
- return hctx;
- return NULL;
-}
-
static int ublk_ctrl_get_queue_affinity(struct io_uring_cmd *cmd)
{
struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
void __user *argp = (void __user *)(unsigned long)header->addr;
- struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_queue_map qmap = {};
+ cpumask_var_t cpumask;
struct ublk_device *ub;
unsigned long queue;
unsigned int retlen;
+ unsigned int i;
int ret = -EINVAL;
if (header->len * BITS_PER_BYTE < nr_cpu_ids)
@@ -1276,30 +1266,41 @@ static int ublk_ctrl_get_queue_affinity(struct io_uring_cmd *cmd)
ub = ublk_get_device_from_id(header->dev_id);
if (!ub)
- goto out;
+ return -EINVAL;
queue = header->data[0];
if (queue >= ub->dev_info.nr_hw_queues)
- goto out;
- hctx = ublk_get_hw_queue(ub, queue);
- if (!hctx)
- goto out;
+ goto out_put_device;
+
+ qmap.mq_map = kcalloc(nr_cpu_ids, sizeof(qmap.mq_map), GFP_KERNEL);
+ if (!qmap.mq_map)
+ goto out_put_device;
+ qmap.nr_queues = ub->dev_info.nr_hw_queues;
+ blk_mq_map_queues(&qmap);
+
+ ret = -ENOMEM;
+ if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
+ goto out_free_qmap;
+
+ for_each_possible_cpu(i)
+ if (qmap.mq_map[i] == queue)
+ cpumask_set_cpu(i, cpumask);
+ ret = -EFAULT;
retlen = min_t(unsigned short, header->len, cpumask_size());
- if (copy_to_user(argp, hctx->cpumask, retlen)) {
- ret = -EFAULT;
- goto out;
- }
- if (retlen != header->len) {
- if (clear_user(argp + retlen, header->len - retlen)) {
- ret = -EFAULT;
- goto out;
- }
- }
+ if (copy_to_user(argp, cpumask, retlen))
+ goto out_put_device;
+
+ if (retlen != header->len &&
+ clear_user(argp + retlen, header->len - retlen))
+ goto out_put_device;
+
ret = 0;
- out:
- if (ub)
- ublk_put_device(ub);
+ free_cpumask_var(cpumask);
+out_free_qmap:
+ kfree(qmap.mq_map);
+out_put_device:
+ ublk_put_device(ub);
return ret;
}
--
2.30.2
