From 1c0525bfbea6c17044732f5a9b78e0af5ff3eb48 Mon Sep 17 00:00:00 2001 From: Liang Zhen Date: Sun, 15 Sep 2013 23:09:53 +0800 Subject: [PATCH] LU-3055 libcfs: remove page_collection::pc_lock page_collection::pc_lock is supposed to protect race between functions called by smp_call_function(), however we don't have this use-case for ages and page_collection only lives in stack of thread, so it is safe to remove it. Signed-off-by: Liang Zhen Change-Id: I89ca46e6593838d85fc0b91d1ff7c35cc28cf4ce Reviewed-on: http://review.whamcloud.com/7660 Tested-by: Hudson Tested-by: Maloo Reviewed-by: Bobi Jam Reviewed-by: Sebastien Buisson Reviewed-by: Oleg Drokin --- libcfs/libcfs/tracefile.c | 14 -------------- libcfs/libcfs/tracefile.h | 8 -------- 2 files changed, 22 deletions(-) diff --git a/libcfs/libcfs/tracefile.c b/libcfs/libcfs/tracefile.c index 34565c1..e15ec68 100644 --- a/libcfs/libcfs/tracefile.c +++ b/libcfs/libcfs/tracefile.c @@ -201,7 +201,6 @@ static void cfs_tcd_shrink(struct cfs_trace_cpu_data *tcd) pgcount + 1, tcd->tcd_cur_pages); CFS_INIT_LIST_HEAD(&pc.pc_pages); - spin_lock_init(&pc.pc_lock); cfs_list_for_each_entry_safe_typed(tage, tmp, &tcd->tcd_pages, struct cfs_trace_page, linkage) { @@ -529,7 +528,6 @@ static void collect_pages_on_all_cpus(struct page_collection *pc) struct cfs_trace_cpu_data *tcd; int i, cpu; - spin_lock(&pc->pc_lock); cfs_for_each_possible_cpu(cpu) { cfs_tcd_for_each_type_lock(tcd, i, cpu) { cfs_list_splice_init(&tcd->tcd_pages, &pc->pc_pages); @@ -541,7 +539,6 @@ static void collect_pages_on_all_cpus(struct page_collection *pc) } } } - spin_unlock(&pc->pc_lock); } static void collect_pages(struct page_collection *pc) @@ -562,7 +559,6 @@ static void put_pages_back_on_all_cpus(struct page_collection *pc) struct cfs_trace_page *tmp; int i, cpu; - spin_lock(&pc->pc_lock); cfs_for_each_possible_cpu(cpu) { cfs_tcd_for_each_type_lock(tcd, i, cpu) { cur_head = tcd->tcd_pages.next; @@ -582,7 +578,6 @@ static void put_pages_back_on_all_cpus(struct page_collection *pc) } } } - spin_unlock(&pc->pc_lock); } static void put_pages_back(struct page_collection *pc) @@ -601,7 +596,6 @@ static void put_pages_on_tcd_daemon_list(struct page_collection *pc, struct cfs_trace_page *tage; struct cfs_trace_page *tmp; - spin_lock(&pc->pc_lock); cfs_list_for_each_entry_safe_typed(tage, tmp, &pc->pc_pages, struct cfs_trace_page, linkage) { @@ -626,7 +620,6 @@ static void put_pages_on_tcd_daemon_list(struct page_collection *pc, tcd->tcd_cur_daemon_pages--; } } - spin_unlock(&pc->pc_lock); } static void put_pages_on_daemon_list(struct page_collection *pc) @@ -646,8 +639,6 @@ void cfs_trace_debug_print(void) struct cfs_trace_page *tage; struct cfs_trace_page *tmp; - spin_lock_init(&pc.pc_lock); - pc.pc_want_daemon_pages = 1; collect_pages(&pc); cfs_list_for_each_entry_safe_typed(tage, tmp, &pc.pc_pages, @@ -701,7 +692,6 @@ int cfs_tracefile_dump_all_pages(char *filename) goto out; } - spin_lock_init(&pc.pc_lock); pc.pc_want_daemon_pages = 1; collect_pages(&pc); if (cfs_list_empty(&pc.pc_pages)) { @@ -746,8 +736,6 @@ void cfs_trace_flush_pages(void) struct cfs_trace_page *tage; struct cfs_trace_page *tmp; - spin_lock_init(&pc.pc_lock); - pc.pc_want_daemon_pages = 1; collect_pages(&pc); cfs_list_for_each_entry_safe_typed(tage, tmp, &pc.pc_pages, @@ -993,7 +981,6 @@ static int tracefiled(void *arg) /* we're started late enough that we pick up init's fs context */ /* this is so broken in uml? what on earth is going on? */ - spin_lock_init(&pc.pc_lock); complete(&tctl->tctl_start); while (1) { @@ -1195,7 +1182,6 @@ static void cfs_trace_cleanup(void) struct page_collection pc; CFS_INIT_LIST_HEAD(&pc.pc_pages); - spin_lock_init(&pc.pc_lock); trace_cleanup_on_all_cpus(); diff --git a/libcfs/libcfs/tracefile.h b/libcfs/libcfs/tracefile.h index b109e8c..513ee17 100644 --- a/libcfs/libcfs/tracefile.h +++ b/libcfs/libcfs/tracefile.h @@ -205,14 +205,6 @@ extern union cfs_trace_data_union (*cfs_trace_data[TCD_MAX_TYPES])[NR_CPUS]; struct page_collection { cfs_list_t pc_pages; /* - * spin-lock protecting ->pc_pages. It is taken by smp_call_function() - * call-back functions. XXX nikita: Which is horrible: all processors - * receive NMI at the same time only to be serialized by this - * lock. Probably ->pc_pages should be replaced with an array of - * NR_CPUS elements accessed locklessly. - */ - spinlock_t pc_lock; - /* * if this flag is set, collect_pages() will spill both * ->tcd_daemon_pages and ->tcd_pages to the ->pc_pages. Otherwise, * only ->tcd_pages are spilled. -- 1.8.3.1