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IB/ipath: Use counters in ipath_poll and cleanup interrupts in ipath_…
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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>
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Arthur Jones authored and Roland Dreier committed Oct 10, 2007
1 parent 542869a commit 70c51da
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Showing 3 changed files with 57 additions and 51 deletions.
67 changes: 41 additions & 26 deletions drivers/infiniband/hw/ipath/ipath_file_ops.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1341,6 +1341,19 @@ static int ipath_mmap(struct file *fp, struct vm_area_struct *vma)
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)
Expand All @@ -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);
}

Expand All @@ -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);
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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
Expand Down
33 changes: 10 additions & 23 deletions drivers/infiniband/hw/ipath/ipath_intr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
}
}
}
Expand Down Expand Up @@ -960,29 +952,24 @@ 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) &
dd->ipath_i_rcvurg_mask);
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);
}
}
Expand Down
8 changes: 6 additions & 2 deletions drivers/infiniband/hw/ipath/ipath_kernel.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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[] */
Expand Down Expand Up @@ -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);
Expand Down

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