IB/ipath: Make ipath_portdata work with struct pid * not pid_t

The official reason is "with the presence of pid namespaces in the
kernel using pid_t-s inside one is no longer safe."

But the reason I fix this right now is the following:

About a month ago (when 2.6.25 was not yet released) there still was a
one last caller of a to-be-deprecated-soon function find_pid() - the
kill_proc() function, which in turn was only used by nfs callback
code.

During the last merge window, this last caller was finally eliminated
by some NFS patch(es) and I was about to finally kill this kill_proc()
and find_pid(), but found, that I was late and the kill_proc is now
called from the ipath driver since commit 58411d1c ("IB/ipath: Head of
Line blocking vs forward progress of user apps").

So here's a patch that fixes this code to use struct pid * and (!)
the kill_pid routine.

Signed-off-by: Pavel Emelyanov <[e-mail]>
Signed-off-by: Roland Dreier <[e-mail]>

drivers/infiniband/hw/ipath/ipath_driver.c

···
 				ipath_dbg("unit %u port %d is in use "
 					  "(PID %u cmd %s), can't reset\n",
 					  unit, i,
-					  dd->ipath_pd[i]->port_pid,
+					  pid_nr(dd->ipath_pd[i]->port_pid),
 					  dd->ipath_pd[i]->port_comm);
 				ret = -EBUSY;
 				goto bail;
···
 static int ipath_signal_procs(struct ipath_devdata *dd, int sig)
 {
 	int i, sub, any = 0;
-	pid_t pid;
+	struct pid *pid;
 
 	if (!dd->ipath_pd)
 		return 0;
 	for (i = 1; i < dd->ipath_cfgports; i++) {
-		if (!dd->ipath_pd[i] || !dd->ipath_pd[i]->port_cnt ||
-		    !dd->ipath_pd[i]->port_pid)
+		if (!dd->ipath_pd[i] || !dd->ipath_pd[i]->port_cnt)
 			continue;
 		pid = dd->ipath_pd[i]->port_pid;
+		if (!pid)
+			continue;
+
 		dev_info(&dd->pcidev->dev, "context %d in use "
 			  "(PID %u), sending signal %d\n",
-			  i, pid, sig);
-		kill_proc(pid, sig, 1);
+			  i, pid_nr(pid), sig);
+		kill_pid(pid, sig, 1);
 		any++;
 		for (sub = 0; sub < INFINIPATH_MAX_SUBPORT; sub++) {
 			pid = dd->ipath_pd[i]->port_subpid[sub];
···
 				continue;
 			dev_info(&dd->pcidev->dev, "sub-context "
 				"%d:%d in use (PID %u), sending "
-				"signal %d\n", i, sub, pid, sig);
-			kill_proc(pid, sig, 1);
+				"signal %d\n", i, sub, pid_nr(pid), sig);
+			kill_pid(pid, sig, 1);
 			any++;
 		}
 	}

drivers/infiniband/hw/ipath/ipath_file_ops.c

···
 			p = dd->ipath_pageshadow[porttid + tid];
 			dd->ipath_pageshadow[porttid + tid] = NULL;
 			ipath_cdbg(VERBOSE, "PID %u freeing TID %u\n",
-				   pd->port_pid, tid);
+				   pid_nr(pd->port_pid), tid);
 			dd->ipath_f_put_tid(dd, &tidbase[tid],
 					    RCVHQ_RCV_TYPE_EXPECTED,
 					    dd->ipath_tidinvalid);
···
 			   port);
 		pd->port_cnt = 1;
 		port_fp(fp) = pd;
-		pd->port_pid = current->pid;
+		pd->port_pid = get_pid(task_pid(current));
 		strncpy(pd->port_comm, current->comm, sizeof(pd->port_comm));
 		ipath_stats.sps_ports++;
 		ret = 0;
···
 			}
 			port_fp(fp) = pd;
 			subport_fp(fp) = pd->port_cnt++;
-			pd->port_subpid[subport_fp(fp)] = current->pid;
+			pd->port_subpid[subport_fp(fp)] =
+				get_pid(task_pid(current));
 			tidcursor_fp(fp) = 0;
 			pd->active_slaves |= 1 << subport_fp(fp);
 			ipath_cdbg(PROC,
 				   "%s[%u] %u sharing %s[%u] unit:port %u:%u\n",
 				   current->comm, current->pid,
 				   subport_fp(fp),
-				   pd->port_comm, pd->port_pid,
+				   pd->port_comm, pid_nr(pd->port_pid),
 				   dd->ipath_unit, pd->port_port);
 			ret = 1;
 			goto done;
···
 		 * the slave(s) don't wait for receive data forever.
 		 */
 		pd->active_slaves &= ~(1 << fd->subport);
-		pd->port_subpid[fd->subport] = 0;
+		put_pid(pd->port_subpid[fd->subport]);
+		pd->port_subpid[fd->subport] = NULL;
 		mutex_unlock(&ipath_mutex);
 		goto bail;
 	}
···
 
 	if (pd->port_hdrqfull) {
 		ipath_cdbg(PROC, "%s[%u] had %u rcvhdrqfull errors "
-			   "during run\n", pd->port_comm, pd->port_pid,
+			   "during run\n", pd->port_comm, pid_nr(pd->port_pid),
 			   pd->port_hdrqfull);
 		pd->port_hdrqfull = 0;
 	}
···
 			unlock_expected_tids(pd);
 		ipath_stats.sps_ports--;
 		ipath_cdbg(PROC, "%s[%u] closed port %u:%u\n",
-			   pd->port_comm, pd->port_pid,
+			   pd->port_comm, pid_nr(pd->port_pid),
 			   dd->ipath_unit, port);
 	}
 
-	pd->port_pid = 0;
+	put_pid(pd->port_pid);
+	pd->port_pid = NULL;
 	dd->ipath_pd[pd->port_port] = NULL; /* before releasing mutex */
 	mutex_unlock(&ipath_mutex);
 	ipath_free_pddata(dd, pd); /* after releasing the mutex */

drivers/infiniband/hw/ipath/ipath_kernel.h

···
 	/* saved total number of polled urgent packets for poll edge trigger */
 	u32 port_urgent_poll;
 	/* pid of process using this port */
-	pid_t port_pid;
-	pid_t port_subpid[INFINIPATH_MAX_SUBPORT];
+	struct pid *port_pid;
+	struct pid *port_subpid[INFINIPATH_MAX_SUBPORT];
 	/* same size as task_struct .comm[] */
 	char port_comm[16];
 	/* pkeys set by this use of this port */