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iw_cxgb4: Fix possible circular dependency locking warning

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Locking sequence of iw_cxgb4 and RoCE drivers in ib_register_device() is
slightly different and this leads to possible circular dependency locking
warning when both the devices are brought up.

Here is the locking sequence upto ib_register_device():
iw_cxgb4: rtnl_mutex(net stack) --> uld_mutex --> device_mutex
RoCE drivers: device_mutex --> rtnl_mutex

Here is the possibility of cross locking:

	CPU #0 (iw_cxgb4) 		     CPU #1 (RoCE drivers)

-> on interface up cxgb4_up()
executed with rtnl_mutex held
-> hold uld_mutex and try
registering ib device
					-> In ib_register_device() hold
					   device_mutex
-> hold device mutex in
ib_register_device
					-> try acquiring rtnl_mutex in
					   ib_enum_roce_netdev()

Current patch schedules the ib_register_device() functionality of
iw_cxgb4 to a workqueue to prevent the possible cross-locking.
Also rename the labels in c4iw_reister_device().

Signed-off-by: Potnuri Bharat Teja <bharat@chelsio.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Bharat Potnuri
2017-11-09 17:47:33 +05:30
committed by Doug Ledford
parent 84511455ac
commit 1c8f1da5d8
3 changed files with 39 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
drivers/infiniband/hw/cxgb4/device.c
View File

@@ -64,14 +64,9 @@ module_param(c4iw_wr_log_size_order, int, 0444);
MODULE_PARM_DESC(c4iw_wr_log_size_order,
"Number of entries (log2) in the work request timing log.");
struct uld_ctx {
struct list_head entry;
struct cxgb4_lld_info lldi;
struct c4iw_dev *dev;
};
static LIST_HEAD(uld_ctx_list);
static DEFINE_MUTEX(dev_mutex);
struct workqueue_struct *reg_workq;
#define DB_FC_RESUME_SIZE 64
#define DB_FC_RESUME_DELAY 1
@@ -912,7 +907,7 @@ static void c4iw_rdev_close(struct c4iw_rdev *rdev)
c4iw_destroy_resource(&rdev->resource);
}
static void c4iw_dealloc(struct uld_ctx *ctx)
void c4iw_dealloc(struct uld_ctx *ctx)
{
c4iw_rdev_close(&ctx->dev->rdev);
WARN_ON_ONCE(!idr_is_empty(&ctx->dev->cqidr));
@@ -1208,8 +1203,6 @@ static int c4iw_uld_state_change(void *handle, enum cxgb4_state new_state)
case CXGB4_STATE_UP:
pr_info("%s: Up\n", pci_name(ctx->lldi.pdev));
if (!ctx->dev) {
int ret;
ctx->dev = c4iw_alloc(&ctx->lldi);
if (IS_ERR(ctx->dev)) {
pr_err("%s: initialization failed: %ld\n",
@@ -1218,12 +1211,9 @@ static int c4iw_uld_state_change(void *handle, enum cxgb4_state new_state)
ctx->dev = NULL;
break;
}
ret = c4iw_register_device(ctx->dev);
if (ret) {
pr_err("%s: RDMA registration failed: %d\n",
pci_name(ctx->lldi.pdev), ret);
c4iw_dealloc(ctx);
}
INIT_WORK(&ctx->reg_work, c4iw_register_device);
queue_work(reg_workq, &ctx->reg_work);
}
break;
case CXGB4_STATE_DOWN:
@@ -1551,6 +1541,12 @@ static int __init c4iw_init_module(void)
if (!c4iw_debugfs_root)
pr_warn("could not create debugfs entry, continuing\n");
reg_workq = create_singlethread_workqueue("Register_iWARP_device");
if (!reg_workq) {
pr_err("Failed creating workqueue to register iwarp device\n");
return -ENOMEM;
}
cxgb4_register_uld(CXGB4_ULD_RDMA, &c4iw_uld_info);
return 0;
@@ -1567,6 +1563,8 @@ static void __exit c4iw_exit_module(void)
kfree(ctx);
}
mutex_unlock(&dev_mutex);
flush_workqueue(reg_workq);
destroy_workqueue(reg_workq);
cxgb4_unregister_uld(CXGB4_ULD_RDMA);
c4iw_cm_term();
debugfs_remove_recursive(c4iw_debugfs_root);