| Message ID | 1416860092-11620-1-git-send-email-mitchelh@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> -----Original Message----- > From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel- > owner@vger.kernel.org] On Behalf Of Mitchel Humpherys > Sent: Monday, 24 November, 2014 2:15 PM ... > From: Matt Wagantall <mattw@codeaurora.org> > > It is sometimes necessary to poll a memory-mapped register until its value > satisfies some condition. Introduce a family of convenience macros that do > this. Tight-looping, sleeping, and timing out can all be accomplished > using these macros. > ... > +#define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us) \ > +({ \ > + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ > + might_sleep_if(sleep_us); \ > + for (;;) { \ > + (val) = op(addr); \ > + if (cond) \ > + break; \ > + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { > \ > + (val) = op(addr); \ > + break; \ > + } \ > + if (sleep_us) \ > + usleep_range((sleep_us >> 2) + 1, sleep_us); \ The hpsa SCSI driver used to use usleep_range in a loop like that, but we found that it caused scheduler problems during boots because it uses TASK_UNINTERRUPTIBLE: [ 9.260668] [sched_delayed] sched: RT throttling activated msleep() worked much better. --- Rob Elliott HP Server Storage
On Mon, Nov 24 2014 at 04:53:19 PM, "Elliott, Robert (Server Storage)" <Elliott@hp.com> wrote: >> -----Original Message----- >> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel- >> owner@vger.kernel.org] On Behalf Of Mitchel Humpherys >> Sent: Monday, 24 November, 2014 2:15 PM > ... >> From: Matt Wagantall <mattw@codeaurora.org> >> >> It is sometimes necessary to poll a memory-mapped register until its value >> satisfies some condition. Introduce a family of convenience macros that do >> this. Tight-looping, sleeping, and timing out can all be accomplished >> using these macros. >> > ... >> +#define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us) \ >> +({ \ >> + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ >> + might_sleep_if(sleep_us); \ >> + for (;;) { \ >> + (val) = op(addr); \ >> + if (cond) \ >> + break; \ >> + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { >> \ >> + (val) = op(addr); \ >> + break; \ >> + } \ >> + if (sleep_us) \ >> + usleep_range((sleep_us >> 2) + 1, sleep_us); \ > > The hpsa SCSI driver used to use usleep_range in a loop like > that, but we found that it caused scheduler problems during > boots because it uses TASK_UNINTERRUPTIBLE: > [ 9.260668] [sched_delayed] sched: RT throttling activated > > msleep() worked much better. Hmm, maybe you were just sleeping for too long? According to Documentation/timers/timers-howto.txt, usleep_range is what should be used for non-atomic sleeps in the range [10us, 20ms]. Plus we need microsecond granularity anyways, so msleep wouldn't cut it. If there are any potential users of these macros that would want to sleep for more than 20ms I guess we could add a special case here to use msleep when sleep_us exceeds 20,000 or so. -Mitch
> -----Original Message----- > From: Mitchel Humpherys [mailto:mitchelh@codeaurora.org] > Sent: Monday, November 24, 2014 7:21 PM > To: Elliott, Robert (Server Storage) ... > > The hpsa SCSI driver used to use usleep_range in a loop like > > that, but we found that it caused scheduler problems during > > boots because it uses TASK_UNINTERRUPTIBLE: > > [ 9.260668] [sched_delayed] sched: RT throttling activated > > > > msleep() worked much better. Sorry, that might have been msleep_interruptible() - the fixes are still not upstream, so I'll have to doublecheck tomorrow. > Hmm, maybe you were just sleeping for too long? According to > Documentation/timers/timers-howto.txt, usleep_range is what should be > used for non-atomic sleeps in the range [10us, 20ms]. Plus we need > microsecond granularity anyways, so msleep wouldn't cut it. The intervals and the overall number of loops were indeed long. I think the corrected code waits a total of 1 second; before the fix, 600 seconds. > If there are any potential users of these macros that would want to > sleep for more than 20ms I guess we could add a special case here to use > msleep when sleep_us exceeds 20,000 or so. ... Maybe just a comment in the documentation for the macro would suffice, possibly with a separate macro for longer interval sleeps. I don't want to force an extra msleep() call to be compiled into a bunch of places where it's not needed. --- Rob Elliott HP Server Storage
On Mon, Nov 24, 2014 at 08:14:52PM +0000, Mitchel Humpherys wrote: > From: Matt Wagantall <mattw@codeaurora.org> > > It is sometimes necessary to poll a memory-mapped register until its value > satisfies some condition. Introduce a family of convenience macros that do > this. Tight-looping, sleeping, and timing out can all be accomplished using > these macros. > > Cc: Thierry Reding <thierry.reding@gmail.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Matt Wagantall <mattw@codeaurora.org> > Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org> > --- > This patch was originally part of a series [1] for adding support for IOMMU > address translations through an ARM SMMU hardware register. The other > patch in the series (the one that actually uses these macros and implements > said hardware address translations) was Ack'd by the driver maintainer > there (Will Deacon) so I've pulled this patch out to avoid resending an > already Ack'd patch over and over again. > > In short, please see [1] for previous discussion and the first user of > these macros. > > This patch has been resent previously here [2], here [3], and here [4] on > 2014-10-30, 2014-11-06, and 2014-11-17, respectively. It has not changed > since [2] and has not received any comments since [1] on 2014-10-19. > Thanks to everyone who has taken a look at this. > > [1] http://thread.gmane.org/gmane.linux.kernel.iommu/7140 > [2] http://thread.gmane.org/gmane.linux.kernel/1818213 > [3] http://thread.gmane.org/gmane.linux.kernel/1823422 > [4] http://thread.gmane.org/gmane.linux.kernel.iommu/7394 Did this ever get queued? It would be pretty useful for a bunch of drivers that seem to copy-paste this sort of code. If it helps: Acked-by: Will Deacon <will.deacon@arm.com> Will > Changes since v7: > - sorted helper macros by size (b, w, l, q) > - removed some of the more esoteric (or flat-out bogus) helper macros > --- > include/linux/iopoll.h | 140 +++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 140 insertions(+) > create mode 100644 include/linux/iopoll.h > > diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h > new file mode 100644 > index 0000000000..bd161dae2d > --- /dev/null > +++ b/include/linux/iopoll.h > @@ -0,0 +1,140 @@ > +/* > + * Copyright (c) 2012-2014 The Linux Foundation. All rights reserved. > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 and > + * only version 2 as published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + */ > + > +#ifndef _LINUX_IOPOLL_H > +#define _LINUX_IOPOLL_H > + > +#include <linux/kernel.h> > +#include <linux/types.h> > +#include <linux/hrtimer.h> > +#include <linux/delay.h> > +#include <linux/errno.h> > +#include <linux/io.h> > + > +/** > + * readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs > + * @op: accessor function (takes @addr as its only argument) > + * @addr: Address to poll > + * @val: Variable to read the value into > + * @cond: Break condition (usually involving @val) > + * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops) > + * @timeout_us: Timeout in us, 0 means never timeout > + * > + * Returns 0 on success and -ETIMEDOUT upon a timeout. In either > + * case, the last read value at @addr is stored in @val. Must not > + * be called from atomic context if sleep_us or timeout_us are used. > + * > + * When available, you'll probably want to use one of the specialized > + * macros defined below rather than this macro directly. > + */ > +#define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us) \ > +({ \ > + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ > + might_sleep_if(sleep_us); \ > + for (;;) { \ > + (val) = op(addr); \ > + if (cond) \ > + break; \ > + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ > + (val) = op(addr); \ > + break; \ > + } \ > + if (sleep_us) \ > + usleep_range((sleep_us >> 2) + 1, sleep_us); \ > + } \ > + (cond) ? 0 : -ETIMEDOUT; \ > +}) > + > +/** > + * readx_poll_timeout_atomic - Periodically poll an address until a condition is met or a timeout occurs > + * @op: accessor function (takes @addr as its only argument) > + * @addr: Address to poll > + * @val: Variable to read the value into > + * @cond: Break condition (usually involving @val) > + * @delay_us: Time to udelay between reads in us (0 tight-loops) > + * @timeout_us: Timeout in us, 0 means never timeout > + * > + * Returns 0 on success and -ETIMEDOUT upon a timeout. In either > + * case, the last read value at @addr is stored in @val. > + * > + * When available, you'll probably want to use one of the specialized > + * macros defined below rather than this macro directly. > + */ > +#define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \ > +({ \ > + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ > + for (;;) { \ > + (val) = op(addr); \ > + if (cond) \ > + break; \ > + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ > + (val) = op(addr); \ > + break; \ > + } \ > + if (delay_us) \ > + udelay(delay_us); \ > + } \ > + (cond) ? 0 : -ETIMEDOUT; \ > +}) > + > + > +#define readb_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readb, addr, val, cond, delay_us, timeout_us) > + > +#define readb_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readb, addr, val, cond, delay_us, timeout_us) > + > +#define readw_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readw, addr, val, cond, delay_us, timeout_us) > + > +#define readw_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readw, addr, val, cond, delay_us, timeout_us) > + > +#define readl_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readl, addr, val, cond, delay_us, timeout_us) > + > +#define readl_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readl, addr, val, cond, delay_us, timeout_us) > + > +#define readq_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readq, addr, val, cond, delay_us, timeout_us) > + > +#define readq_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readq, addr, val, cond, delay_us, timeout_us) > + > +#define readb_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readb_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readb_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readb_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readw_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readw_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readw_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readw_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readl_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readl_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readl_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readl_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readq_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout(readq_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#define readq_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ > + readx_poll_timeout_atomic(readq_relaxed, addr, val, cond, delay_us, timeout_us) > + > +#endif /* _LINUX_IOPOLL_H */ > -- > Qualcomm Innovation Center, Inc. > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project > >
diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h new file mode 100644 index 0000000000..bd161dae2d --- /dev/null +++ b/include/linux/iopoll.h @@ -0,0 +1,140 @@ +/* + * Copyright (c) 2012-2014 The Linux Foundation. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 and + * only version 2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + +#ifndef _LINUX_IOPOLL_H +#define _LINUX_IOPOLL_H + +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/hrtimer.h> +#include <linux/delay.h> +#include <linux/errno.h> +#include <linux/io.h> + +/** + * readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs + * @op: accessor function (takes @addr as its only argument) + * @addr: Address to poll + * @val: Variable to read the value into + * @cond: Break condition (usually involving @val) + * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops) + * @timeout_us: Timeout in us, 0 means never timeout + * + * Returns 0 on success and -ETIMEDOUT upon a timeout. In either + * case, the last read value at @addr is stored in @val. Must not + * be called from atomic context if sleep_us or timeout_us are used. + * + * When available, you'll probably want to use one of the specialized + * macros defined below rather than this macro directly. + */ +#define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us) \ +({ \ + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ + might_sleep_if(sleep_us); \ + for (;;) { \ + (val) = op(addr); \ + if (cond) \ + break; \ + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ + (val) = op(addr); \ + break; \ + } \ + if (sleep_us) \ + usleep_range((sleep_us >> 2) + 1, sleep_us); \ + } \ + (cond) ? 0 : -ETIMEDOUT; \ +}) + +/** + * readx_poll_timeout_atomic - Periodically poll an address until a condition is met or a timeout occurs + * @op: accessor function (takes @addr as its only argument) + * @addr: Address to poll + * @val: Variable to read the value into + * @cond: Break condition (usually involving @val) + * @delay_us: Time to udelay between reads in us (0 tight-loops) + * @timeout_us: Timeout in us, 0 means never timeout + * + * Returns 0 on success and -ETIMEDOUT upon a timeout. In either + * case, the last read value at @addr is stored in @val. + * + * When available, you'll probably want to use one of the specialized + * macros defined below rather than this macro directly. + */ +#define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \ +({ \ + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ + for (;;) { \ + (val) = op(addr); \ + if (cond) \ + break; \ + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ + (val) = op(addr); \ + break; \ + } \ + if (delay_us) \ + udelay(delay_us); \ + } \ + (cond) ? 0 : -ETIMEDOUT; \ +}) + + +#define readb_poll_timeout(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readb, addr, val, cond, delay_us, timeout_us) + +#define readb_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readb, addr, val, cond, delay_us, timeout_us) + +#define readw_poll_timeout(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readw, addr, val, cond, delay_us, timeout_us) + +#define readw_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readw, addr, val, cond, delay_us, timeout_us) + +#define readl_poll_timeout(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readl, addr, val, cond, delay_us, timeout_us) + +#define readl_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readl, addr, val, cond, delay_us, timeout_us) + +#define readq_poll_timeout(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readq, addr, val, cond, delay_us, timeout_us) + +#define readq_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readq, addr, val, cond, delay_us, timeout_us) + +#define readb_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readb_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readb_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readb_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readw_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readw_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readw_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readw_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readl_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readl_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readl_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readl_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readq_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readq_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readq_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readq_relaxed, addr, val, cond, delay_us, timeout_us) + +#endif /* _LINUX_IOPOLL_H */