IB/ipath: Use counters in ipath_poll and cleanup interrupts in ipath_close

ipath_poll() suffered from a couple subtle bugs.  Under the right
conditions we could leave recv interrupts enabled on an ipath user
context on close, thereby taking potentially unwanted interrupts on the
next open -- this is fixed by unconditionally turning off recv
interrupts on close.  Also, we now use counters rather than set/clear
bits which allows us to make sure we catch all interrupts at the cost of
changing the semantics slightly (it's now give me all events since the
last time I called poll() rather than give me all events since I called
_this_ poll routine).  We also added some memory barriers which may help
ensure we get all notifications in a timely manner.

Signed-off-by: Arthur Jones <arthur.jones@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

3 files changed, 57 insertions, 51 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_file_ops.c b/drivers/infiniband/hw/ipath/ipath_file_ops.c
index 33ab0d6b80ff..016e7c4e366b 100644
--- a/drivers/infiniband/hw/ipath/ipath_file_ops.c
+++ b/drivers/infiniband/hw/ipath/ipath_file_ops.c
@@ -1341,6 +1341,19 @@ bail:
         return ret;
 }
 
+static unsigned ipath_poll_hdrqfull(struct ipath_portdata *pd)
+{
+        unsigned pollflag = 0;
+
+        if ((pd->poll_type & IPATH_POLL_TYPE_OVERFLOW) &&
+            pd->port_hdrqfull != pd->port_hdrqfull_poll) {
+                pollflag |= POLLIN | POLLRDNORM;
+                pd->port_hdrqfull_poll = pd->port_hdrqfull;
+        }
+
+        return pollflag;
+}
+
 static unsigned int ipath_poll_urgent(struct ipath_portdata *pd,
                                       struct file *fp,
                                       struct poll_table_struct *pt)
@@ -1350,22 +1363,20 @@ static unsigned int ipath_poll_urgent(struct ipath_portdata *pd,
 
         dd = pd->port_dd;
 
-        if (test_bit(IPATH_PORT_WAITING_OVERFLOW, &pd->int_flag)) {
-                pollflag |= POLLERR;
-                clear_bit(IPATH_PORT_WAITING_OVERFLOW, &pd->int_flag);
-        }
+        /* variable access in ipath_poll_hdrqfull() needs this */
+        rmb();
+        pollflag = ipath_poll_hdrqfull(pd);
 
-        if (test_bit(IPATH_PORT_WAITING_URG, &pd->int_flag)) {
+        if (pd->port_urgent != pd->port_urgent_poll) {
                 pollflag |= POLLIN | POLLRDNORM;
-                clear_bit(IPATH_PORT_WAITING_URG, &pd->int_flag);
+                pd->port_urgent_poll = pd->port_urgent;
         }
 
         if (!pollflag) {
+                /* this saves a spin_lock/unlock in interrupt handler... */
                 set_bit(IPATH_PORT_WAITING_URG, &pd->port_flag);
-                if (pd->poll_type & IPATH_POLL_TYPE_OVERFLOW)
-                        set_bit(IPATH_PORT_WAITING_OVERFLOW,
-                                &pd->port_flag);
-
+                /* flush waiting flag so don't miss an event... */
+                wmb();
                 poll_wait(fp, &pd->port_wait, pt);
         }
 
@@ -1376,31 +1387,27 @@ static unsigned int ipath_poll_next(struct ipath_portdata *pd,
                                     struct file *fp,
                                     struct poll_table_struct *pt)
 {
-        u32 head, tail;
+        u32 head;
+        u32 tail;
         unsigned pollflag = 0;
         struct ipath_devdata *dd;
 
         dd = pd->port_dd;
 
+        /* variable access in ipath_poll_hdrqfull() needs this */
+        rmb();
+        pollflag = ipath_poll_hdrqfull(pd);
+
         head = ipath_read_ureg32(dd, ur_rcvhdrhead, pd->port_port);
         tail = *(volatile u64 *)pd->port_rcvhdrtail_kvaddr;
 
-        if (test_bit(IPATH_PORT_WAITING_OVERFLOW, &pd->int_flag)) {
-                pollflag |= POLLERR;
-                clear_bit(IPATH_PORT_WAITING_OVERFLOW, &pd->int_flag);
-        }
-
-        if (tail != head ||
-            test_bit(IPATH_PORT_WAITING_RCV, &pd->int_flag)) {
+        if (head != tail)
                 pollflag |= POLLIN | POLLRDNORM;
-                clear_bit(IPATH_PORT_WAITING_RCV, &pd->int_flag);
-        }
-
-        if (!pollflag) {
+        else {
+                /* this saves a spin_lock/unlock in interrupt handler */
                 set_bit(IPATH_PORT_WAITING_RCV, &pd->port_flag);
-                if (pd->poll_type & IPATH_POLL_TYPE_OVERFLOW)
-                        set_bit(IPATH_PORT_WAITING_OVERFLOW,
-                                &pd->port_flag);
+                /* flush waiting flag so we don't miss an event */
+                wmb();
 
                 set_bit(pd->port_port + INFINIPATH_R_INTRAVAIL_SHIFT,
                         &dd->ipath_rcvctrl);
@@ -1917,6 +1924,12 @@ static int ipath_do_user_init(struct file *fp,
         ipath_cdbg(VERBOSE, "Wrote port%d egrhead %x from tail regs\n",
                 pd->port_port, head32);
         pd->port_tidcursor = 0; /* start at beginning after open */
+
+        /* initialize poll variables... */
+        pd->port_urgent = 0;
+        pd->port_urgent_poll = 0;
+        pd->port_hdrqfull_poll = pd->port_hdrqfull;
+
         /*
          * now enable the port; the tail registers will be written to memory
          * by the chip as soon as it sees the write to
@@ -2039,9 +2052,11 @@ static int ipath_close(struct inode *in, struct file *fp)
 
         if (dd->ipath_kregbase) {
                 int i;
-                /* atomically clear receive enable port. */
+                /* atomically clear receive enable port and intr avail. */
                 clear_bit(INFINIPATH_R_PORTENABLE_SHIFT + port,
                           &dd->ipath_rcvctrl);
+                clear_bit(pd->port_port + INFINIPATH_R_INTRAVAIL_SHIFT,
+                          &dd->ipath_rcvctrl);
                 ipath_write_kreg( dd, dd->ipath_kregs->kr_rcvctrl,
                         dd->ipath_rcvctrl);
                 /* and read back from chip to be sure that nothing
diff --git a/drivers/infiniband/hw/ipath/ipath_intr.c b/drivers/infiniband/hw/ipath/ipath_intr.c
index 11b361408ae6..61eac8cc0d9f 100644
--- a/drivers/infiniband/hw/ipath/ipath_intr.c
+++ b/drivers/infiniband/hw/ipath/ipath_intr.c
@@ -688,17 +688,9 @@ static int handle_errors(struct ipath_devdata *dd, ipath_err_t errs)
                                         chkerrpkts = 1;
                                 dd->ipath_lastrcvhdrqtails[i] = tl;
                                 pd->port_hdrqfull++;
-                                if (test_bit(IPATH_PORT_WAITING_OVERFLOW,
-                                             &pd->port_flag)) {
-                                        clear_bit(
-                                          IPATH_PORT_WAITING_OVERFLOW,
-                                          &pd->port_flag);
-                                        set_bit(
-                                          IPATH_PORT_WAITING_OVERFLOW,
-                                          &pd->int_flag);
-                                        wake_up_interruptible(
-                                          &pd->port_wait);
-                                }
+                                /* flush hdrqfull so that poll() sees it */
+                                wmb();
+                                wake_up_interruptible(&pd->port_wait);
                         }
                 }
         }
@@ -960,6 +952,8 @@ static void handle_urcv(struct ipath_devdata *dd, u32 istat)
         int i;
         int rcvdint = 0;
 
+        /* test_bit below needs this... */
+        rmb();
         portr = ((istat >> INFINIPATH_I_RCVAVAIL_SHIFT) &
                  dd->ipath_i_rcvavail_mask)
                 | ((istat >> INFINIPATH_I_RCVURG_SHIFT) &
@@ -967,22 +961,15 @@ static void handle_urcv(struct ipath_devdata *dd, u32 istat)
         for (i = 1; i < dd->ipath_cfgports; i++) {
                 struct ipath_portdata *pd = dd->ipath_pd[i];
                 if (portr & (1 << i) && pd && pd->port_cnt) {
-                        if (test_bit(IPATH_PORT_WAITING_RCV,
-                                     &pd->port_flag)) {
-                                clear_bit(IPATH_PORT_WAITING_RCV,
-                                          &pd->port_flag);
-                                set_bit(IPATH_PORT_WAITING_RCV,
-                                        &pd->int_flag);
+                        if (test_and_clear_bit(IPATH_PORT_WAITING_RCV,
+                                               &pd->port_flag)) {
                                 clear_bit(i + INFINIPATH_R_INTRAVAIL_SHIFT,
                                           &dd->ipath_rcvctrl);
                                 wake_up_interruptible(&pd->port_wait);
                                 rcvdint = 1;
-                        } else if (test_bit(IPATH_PORT_WAITING_URG,
-                                            &pd->port_flag)) {
-                                clear_bit(IPATH_PORT_WAITING_URG,
-                                          &pd->port_flag);
-                                set_bit(IPATH_PORT_WAITING_URG,
-                                        &pd->int_flag);
+                        } else if (test_and_clear_bit(IPATH_PORT_WAITING_URG,
+                                                      &pd->port_flag)) {
+                                pd->port_urgent++;
                                 wake_up_interruptible(&pd->port_wait);
                         }
                 }
diff --git a/drivers/infiniband/hw/ipath/ipath_kernel.h b/drivers/infiniband/hw/ipath/ipath_kernel.h
index d983f92b9bcb..872fb36703d9 100644
--- a/drivers/infiniband/hw/ipath/ipath_kernel.h
+++ b/drivers/infiniband/hw/ipath/ipath_kernel.h
@@ -139,6 +139,12 @@ struct ipath_portdata {
         u32 port_pionowait;
         /* total number of rcvhdrqfull errors */
         u32 port_hdrqfull;
+        /* saved total number of rcvhdrqfull errors for poll edge trigger */
+        u32 port_hdrqfull_poll;
+        /* total number of polled urgent packets */
+        u32 port_urgent;
+        /* 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;
         /* same size as task_struct .comm[] */
@@ -757,8 +763,6 @@ int ipath_set_rx_pol_inv(struct ipath_devdata *dd, u8 new_pol_inv);
 #define IPATH_PORT_MASTER_UNINIT 4
                 /* waiting for an urgent packet to arrive */
 #define IPATH_PORT_WAITING_URG 5
-                /* waiting for a header overflow */
-#define IPATH_PORT_WAITING_OVERFLOW 6
 
 /* free up any allocated data at closes */
 void ipath_free_data(struct ipath_portdata *dd);