staging: lustre: remove page_collection::pc_lock in libcfs

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 <liang.zhen@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3055
Reviewed-on: http://review.whamcloud.com/7660
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Sebastien Buisson <sebastien.buisson@bull.net>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/libcfs/tracefile.c b/drivers/staging/lustre/lustre/libcfs/tracefile.c
index f99d30f799e0c5cb56225c047abb773e2482a5b4..c27e3207e9325c93555441fdfc73b9e5fff539ee 100644 (file)
--- a/drivers/staging/lustre/lustre/libcfs/tracefile.c
+++ b/drivers/staging/lustre/lustre/libcfs/tracefile.c
@@ -199,7 +199,6 @@ static void cfs_tcd_shrink(struct cfs_trace_cpu_data *tcd)
                       pgcount + 1, tcd->tcd_cur_pages);
 
        INIT_LIST_HEAD(&pc.pc_pages);
-       spin_lock_init(&pc.pc_lock);
 
        list_for_each_entry_safe(tage, tmp, &tcd->tcd_pages, linkage) {
                if (pgcount-- == 0)
@@ -522,7 +521,6 @@ 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);
        for_each_possible_cpu(cpu) {
                cfs_tcd_for_each_type_lock(tcd, i, cpu) {
                        list_splice_init(&tcd->tcd_pages, &pc->pc_pages);
@@ -534,7 +532,6 @@ static void collect_pages_on_all_cpus(struct page_collection *pc)
                        }
                }
        }
-       spin_unlock(&pc->pc_lock);
 }
 
 static void collect_pages(struct page_collection *pc)
@@ -555,7 +552,6 @@ 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);
        for_each_possible_cpu(cpu) {
                cfs_tcd_for_each_type_lock(tcd, i, cpu) {
                        cur_head = tcd->tcd_pages.next;
@@ -573,7 +569,6 @@ 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)
@@ -592,7 +587,6 @@ 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);
        list_for_each_entry_safe(tage, tmp, &pc->pc_pages, linkage) {
 
                __LASSERT_TAGE_INVARIANT(tage);
@@ -616,7 +610,6 @@ 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)
@@ -636,8 +629,6 @@ 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);
        list_for_each_entry_safe(tage, tmp, &pc.pc_pages, linkage) {
@@ -692,7 +683,6 @@ 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 (list_empty(&pc.pc_pages)) {
@@ -739,8 +729,6 @@ 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);
        list_for_each_entry_safe(tage, tmp, &pc.pc_pages, linkage) {
@@ -970,7 +958,6 @@ 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) {
@@ -1170,7 +1157,6 @@ static void cfs_trace_cleanup(void)
        struct page_collection pc;
 
        INIT_LIST_HEAD(&pc.pc_pages);
-       spin_lock_init(&pc.pc_lock);
 
        trace_cleanup_on_all_cpus();
 

diff --git a/drivers/staging/lustre/lustre/libcfs/tracefile.h b/drivers/staging/lustre/lustre/libcfs/tracefile.h
index 73d60e05692264556ce6b02e2f1e79483f1ec069..e5fbeecf3567dfeacda10591f0b61845d24d88a3 100644 (file)
--- a/drivers/staging/lustre/lustre/libcfs/tracefile.h
+++ b/drivers/staging/lustre/lustre/libcfs/tracefile.h
@@ -195,14 +195,6 @@ extern union cfs_trace_data_union (*cfs_trace_data[TCD_MAX_TYPES])[NR_CPUS];
  * be moved there */
 struct page_collection {
        struct list_head        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,