From 3a2a1e90564e3ad215aa5c6ddc0e741cd6208a93 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Wed, 6 Feb 2019 09:59:17 -0800 Subject: drivers/IB,qib: optimize mmap_sem usage The driver uses mmap_sem for both pinned_vm accounting and get_user_pages(). Because rdma drivers might want to use gup_longterm() in the future we still need some sort of mmap_sem serialization (as opposed to removing it entirely by using gup_fast()). Now that pinned_vm is atomic the writer lock can therefore be converted to reader. This also fixes a bug that __qib_get_user_pages was not taking into account the current value of pinned_vm. Reviewed-by: Ira Weiny Signed-off-by: Davidlohr Bueso Signed-off-by: Jason Gunthorpe --- drivers/infiniband/hw/qib/qib_user_pages.c | 73 +++++++++++------------------- 1 file changed, 27 insertions(+), 46 deletions(-) (limited to 'drivers/infiniband/hw/qib') diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c index c6c81022d313..ef8bcf366ddc 100644 --- a/drivers/infiniband/hw/qib/qib_user_pages.c +++ b/drivers/infiniband/hw/qib/qib_user_pages.c @@ -49,43 +49,6 @@ static void __qib_release_user_pages(struct page **p, size_t num_pages, } } -/* - * Call with current->mm->mmap_sem held. - */ -static int __qib_get_user_pages(unsigned long start_page, size_t num_pages, - struct page **p) -{ - unsigned long lock_limit; - size_t got; - int ret; - - lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; - - if (num_pages > lock_limit && !capable(CAP_IPC_LOCK)) { - ret = -ENOMEM; - goto bail; - } - - for (got = 0; got < num_pages; got += ret) { - ret = get_user_pages_longterm(start_page + got * PAGE_SIZE, - num_pages - got, - FOLL_WRITE | FOLL_FORCE, - p + got, NULL); - if (ret < 0) - goto bail_release; - } - - atomic64_add(num_pages, ¤t->mm->pinned_vm); - - ret = 0; - goto bail; - -bail_release: - __qib_release_user_pages(p, got, 0); -bail: - return ret; -} - /** * qib_map_page - a safety wrapper around pci_map_page() * @@ -137,26 +100,44 @@ int qib_map_page(struct pci_dev *hwdev, struct page *page, dma_addr_t *daddr) int qib_get_user_pages(unsigned long start_page, size_t num_pages, struct page **p) { + unsigned long locked, lock_limit; + size_t got; int ret; - down_write(¤t->mm->mmap_sem); + lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; + locked = atomic64_add_return(num_pages, ¤t->mm->pinned_vm); - ret = __qib_get_user_pages(start_page, num_pages, p); + if (num_pages > lock_limit && !capable(CAP_IPC_LOCK)) { + ret = -ENOMEM; + goto bail; + } - up_write(¤t->mm->mmap_sem); + down_read(¤t->mm->mmap_sem); + for (got = 0; got < num_pages; got += ret) { + ret = get_user_pages_longterm(start_page + got * PAGE_SIZE, + num_pages - got, + FOLL_WRITE | FOLL_FORCE, + p + got, NULL); + if (ret < 0) { + up_read(¤t->mm->mmap_sem); + goto bail_release; + } + } + up_read(¤t->mm->mmap_sem); + return 0; +bail_release: + __qib_release_user_pages(p, got, 0); +bail: + atomic64_sub(num_pages, ¤t->mm->pinned_vm); return ret; } void qib_release_user_pages(struct page **p, size_t num_pages) { - if (current->mm) /* during close after signal, mm can be NULL */ - down_write(¤t->mm->mmap_sem); - __qib_release_user_pages(p, num_pages, 1); - if (current->mm) { + /* during close after signal, mm can be NULL */ + if (current->mm) atomic64_sub(num_pages, ¤t->mm->pinned_vm); - up_write(¤t->mm->mmap_sem); - } } -- cgit v1.2.3