/* * linux/kernel/time/tick-broadcast-hrtimer.c * This file emulates a local clock event device * via a pseudo clock device. */ #include #include #include #include #include #include #include #include #include #include #include "tick-internal.h" static struct hrtimer bctimer; static int bc_shutdown(struct clock_event_device *evt) { /* * Note, we cannot cancel the timer here as we might * run into the following live lock scenario: * * cpu 0 cpu1 * lock(broadcast_lock); * hrtimer_interrupt() * bc_handler() * tick_handle_oneshot_broadcast(); * lock(broadcast_lock); * hrtimer_cancel() * wait_for_callback() */ hrtimer_try_to_cancel(&bctimer); return 0; } /* * This is called from the guts of the broadcast code when the cpu * which is about to enter idle has the earliest broadcast timer event. */ static int bc_set_next(ktime_t expires, struct clock_event_device *bc) { int bc_moved; /* * We try to cancel the timer first. If the callback is on * flight on some other cpu then we let it handle it. If we * were able to cancel the timer nothing can rearm it as we * own broadcast_lock. * * However we can also be called from the event handler of * ce_broadcast_hrtimer itself when it expires. We cannot * restart the timer because we are in the callback, but we * can set the expiry time and let the callback return * HRTIMER_RESTART. * * Since we are in the idle loop at this point and because * hrtimer_{start/cancel} functions call into tracing, * calls to these functions must be bound within RCU_NONIDLE. */ RCU_NONIDLE({ bc_moved = hrtimer_try_to_cancel(&bctimer) >= 0; if (bc_moved) hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED);}); if (bc_moved) { /* Bind the "device" to the cpu */ bc->bound_on = smp_processor_id(); } else if (bc->bound_on == smp_processor_id()) { hrtimer_set_expires(&bctimer, expires); } return 0; } static struct clock_event_device ce_broadcast_hrtimer = { .name = "bc_hrtimer", .set_state_shutdown = bc_shutdown, .set_next_ktime = bc_set_next, .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_KTIME | CLOCK_EVT_FEAT_HRTIMER, .rating = 0, .bound_on = -1, .min_delta_ns = 1, .max_delta_ns = KTIME_MAX, .min_delta_ticks = 1, .max_delta_ticks = ULONG_MAX, .mult = 1, .shift = 0, .cpumask = cpu_all_mask, }; static enum hrtimer_restart bc_handler(struct hrtimer *t) { ce_broadcast_hrtimer.event_handler(&ce_broadcast_hrtimer); if (clockevent_state_oneshot(&ce_broadcast_hrtimer)) if (ce_broadcast_hrtimer.next_event != KTIME_MAX) return HRTIMER_RESTART; return HRTIMER_NORESTART; } void tick_setup_hrtimer_broadcast(void) { hrtimer_init(&bctimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); bctimer.function = bc_handler; clockevents_register_device(&ce_broadcast_hrtimer); } space:mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2016-12-12 21:58:13 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-12 21:58:13 -0800
commite7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba (patch)
treef63906f41699c8e38af9d12b063e2ceab0286ef2 /drivers/usb
parente34bac726d27056081d0250c0e173e4b155aa340 (diff)
parent868c97a846a73e937d835b09b8c885a69df50ec8 (diff)
Merge tag 'docs-4.10' of git://git.lwn.net/linuxHEADmaster
Pull documentation update from Jonathan Corbet: "These are the documentation changes for 4.10. It's another busy cycle for the docs tree, as the sphinx conversion continues. Highlights include: - Further work on PDF output, which remains a bit of a pain but should be more solid now. - Five more DocBook template files converted to Sphinx. Only 27 to go... Lots of plain-text files have also been converted and integrated. - Images in binary formats have been replaced with more source-friendly versions. - Various bits of organizational work, including the renaming of various files discussed at the kernel summit. - New documentation for the device_link mechanism. ... and, of course, lots of typo fixes and small updates" * tag 'docs-4.10' of git://git.lwn.net/linux: (193 commits) dma-buf: Extract dma-buf.rst Update Documentation/00-INDEX docs: 00-INDEX: document directories/files with no docs docs: 00-INDEX: remove non-existing entries docs: 00-INDEX: add missing entries for documentation files/dirs docs: 00-INDEX: consolidate process/ and admin-guide/ description scripts: add a script to check if Documentation/00-INDEX is sane Docs: change sh -> awk in REPORTING-BUGS Documentation/core-api/device_link: Add initial documentation core-api: remove an unexpected unident ppc/idle: Add documentation for powersave=off Doc: Correct typo, "Introdution" => "Introduction" Documentation/atomic_ops.txt: convert to ReST markup Documentation/local_ops.txt: convert to ReST markup Documentation/assoc_array.txt: convert to ReST markup docs-rst: parse-headers.pl: cleanup the documentation docs-rst: fix media cleandocs target docs-rst: media/Makefile: reorganize the rules docs-rst: media: build SVG from graphviz files docs-rst: replace bayer.png by a SVG image ...
Diffstat (limited to 'drivers/usb')