/* * Lockless hierarchical page accounting & limiting * * Copyright (C) 2014 Red Hat, Inc., Johannes Weiner */ #include #include #include #include #include #include #include /** * page_counter_cancel - take pages out of the local counter * @counter: counter * @nr_pages: number of pages to cancel */ void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages) { long new; new = atomic_long_sub_return(nr_pages, &counter->count); /* More uncharges than charges? */ WARN_ON_ONCE(new < 0); } /** * page_counter_charge - hierarchically charge pages * @counter: counter * @nr_pages: number of pages to charge * * NOTE: This does not consider any configured counter limits. */ void page_counter_charge(struct page_counter *counter, unsigned long nr_pages) { struct page_counter *c; for (c = counter; c; c = c->parent) { long new; new = atomic_long_add_return(nr_pages, &c->count); /* * This is indeed racy, but we can live with some * inaccuracy in the watermark. */ if (new > c->watermark) c->watermark = new; } } /** * page_counter_try_charge - try to hierarchically charge pages * @counter: counter * @nr_pages: number of pages to charge * @fail: points first counter to hit its limit, if any * * Returns %true on success, or %false and @fail if the counter or one * of its ancestors has hit its configured limit. */ bool page_counter_try_charge(struct page_counter *counter, unsigned long nr_pages, struct page_counter **fail) { struct page_counter *c; for (c = counter; c; c = c->parent) { long new; /* * Charge speculatively to avoid an expensive CAS. If * a bigger charge fails, it might falsely lock out a * racing smaller charge and send it into reclaim * early, but the error is limited to the difference * between the two sizes, which is less than 2M/4M in * case of a THP locking out a regular page charge. * * The atomic_long_add_return() implies a full memory * barrier between incrementing the count and reading * the limit. When racing with page_counter_limit(), * we either see the new limit or the setter sees the * counter has changed and retries. */ new = atomic_long_add_return(nr_pages, &c->count); if (new > c->limit) { atomic_long_sub(nr_pages, &c->count); /* * This is racy, but we can live with some * inaccuracy in the failcnt. */ c->failcnt++; *fail = c; goto failed; } /* * Just like with failcnt, we can live with some * inaccuracy in the watermark. */ if (new > c->watermark) c->watermark = new; } return true; failed: for (c = counter; c != *fail; c = c->parent) page_counter_cancel(c, nr_pages); return false; } /** * page_counter_uncharge - hierarchically uncharge pages * @counter: counter * @nr_pages: number of pages to uncharge */ void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages) { struct page_counter *c; for (c = counter; c; c = c->parent) page_counter_cancel(c, nr_pages); } /** * page_counter_limit - limit the number of pages allowed * @counter: counter * @limit: limit to set * * Returns 0 on success, -EBUSY if the current number of pages on the * counter already exceeds the specified limit. * * The caller must serialize invocations on the same counter. */ int page_counter_limit(struct page_counter *counter, unsigned long limit) { for (;;) { unsigned long old; long count; /* * Update the limit while making sure that it's not * below the concurrently-changing counter value. * * The xchg implies two full memory barriers before * and after, so the read-swap-read is ordered and * ensures coherency with page_counter_try_charge(): * that function modifies the count before checking * the limit, so if it sees the old limit, we see the * modified counter and retry. */ count = atomic_long_read(&counter->count); if (count > limit) return -EBUSY; old = xchg(&counter->limit, limit); if (atomic_long_read(&counter->count) <= count) return 0; counter->limit = old; cond_resched(); } } /** * page_counter_memparse - memparse() for page counter limits * @buf: string to parse * @max: string meaning maximum possible value * @nr_pages: returns the result in number of pages * * Returns -EINVAL, or 0 and @nr_pages on success. @nr_pages will be * limited to %PAGE_COUNTER_MAX. */ int page_counter_memparse(const char *buf, const char *max, unsigned long *nr_pages) { char *end; u64 bytes; if (!strcmp(buf, max)) { *nr_pages = PAGE_COUNTER_MAX; return 0; } bytes = memparse(buf, &end); if (*end != '\0') return -EINVAL; *nr_pages = min(bytes / PAGE_SIZE, (u64)PAGE_COUNTER_MAX); return 0; } d>
authorStanislaw Gruszka <sgruszka@redhat.com>2017-01-29 12:40:52 +0100
committerKalle Valo <kvalo@codeaurora.org>2017-01-31 09:08:52 +0200
commit33e962c8871f015f5c8978384553dddcf5b81b22 (patch)
tree43aff96c2ee21d9e0fa2018457778a4de52053cd /net/mac80211/debugfs_netdev.h
parent575ddce0507789bf9830d089557d2199d2f91865 (diff)
rt2x00: fix clk_get call
clk_get() takes two arguments and might return ERR_PTR(), so we have to nullify pointer on that case, to do not break further call to clk_get_rate(). Reported-by: Felix Fietkau <nbd@nbd.name> Fixes: 34db70b92fae ("rt2x00: add copy of clk for soc devices") Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Diffstat (limited to 'net/mac80211/debugfs_netdev.h')