[ This is an ancient bug, but the bug is clear to see, but unfortunately
it's probably less easy to fix. - dan ]
Hello Upinder Malhi,
The patch e3cf00d0a87f: "IB/usnic: Add Cisco VIC low-level hardware
driver" from Sep 10, 2013, leads to the following static checker
warning:
fs/kernfs/dir.c:476 kernfs_drain()
warn: sleeping in atomic context
drivers/infiniband/hw/usnic/usnic_ib_verbs.c
190 if (usnic_ib_share_vf) {
191 /* Try to find resouces on a used vf which is in pd */
192 dev_list = usnic_uiom_get_dev_list(pd->umem_pd);
193 if (IS_ERR(dev_list))
194 return ERR_CAST(dev_list);
195 for (i = 0; dev_list[i]; i++) {
196 dev = dev_list[i];
197 vf = dev_get_drvdata(dev);
198 spin_lock(&vf->lock);
^^^^^^^^^^^^^^^^^^^^^
We're holding a spin lock.
199 vnic = vf->vnic;
200 if (!usnic_vnic_check_room(vnic, res_spec)) {
201 usnic_dbg("Found used vnic %s from %s\n",
202 dev_name(&us_ibdev->ib_dev.dev),
203 pci_name(usnic_vnic_get_pdev(
204 vnic)));
205 qp_grp = usnic_ib_qp_grp_create(us_ibdev->ufdev,
^^^^^^^^^^^^^^^^^^^^^^
The create function calls usnic_ib_sysfs_qpn_add() which does a
kobject_init_and_add(). Unfortunately kobject allocations have many
sleeps inside them so it can't be done while holding a spinlock.
Same thing for the other usnic_ib_qp_grp_create() later on in the same
function.
206 vf, pd,
207 res_spec,
208 trans_spec);
209
210 spin_unlock(&vf->lock);
211 goto qp_grp_check;
212 }
213 spin_unlock(&vf->lock);
214
215 }
216 usnic_uiom_free_dev_list(dev_list);
217 dev_list = NULL;
218 }
regards,
dan carpenter
