From b38f6c50270683abf35a388f82cafecce971a003 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Wed, 20 Feb 2019 11:30:49 -0500 Subject: XArray: Fix xa_release in allocating arrays xa_cmpxchg() was a little too magic in turning ZERO entries into NULL, and would leave the entry set to the ZERO entry instead of releasing it for future use. After careful review of existing users of xa_cmpxchg(), change the semantics so that it does not translate either incoming argument from NULL into ZERO entries. Add several tests to the test-suite to make sure this problem doesn't come back. Reported-by: Jason Gunthorpe Signed-off-by: Matthew Wilcox --- lib/test_xarray.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) (limited to 'lib/test_xarray.c') diff --git a/lib/test_xarray.c b/lib/test_xarray.c index 3eaa40ddc390..52f8ecff8c0c 100644 --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -361,6 +361,7 @@ static noinline void check_reserve(struct xarray *xa) { void *entry; unsigned long index; + int count; /* An array with a reserved entry is not empty */ XA_BUG_ON(xa, !xa_empty(xa)); @@ -377,15 +378,15 @@ static noinline void check_reserve(struct xarray *xa) xa_erase_index(xa, 12345678); XA_BUG_ON(xa, !xa_empty(xa)); - /* cmpxchg sees a reserved entry as NULL */ + /* cmpxchg sees a reserved entry as ZERO */ XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0); - XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, NULL, xa_mk_value(12345678), - GFP_NOWAIT) != NULL); + XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, XA_ZERO_ENTRY, + xa_mk_value(12345678), GFP_NOWAIT) != NULL); xa_release(xa, 12345678); xa_erase_index(xa, 12345678); XA_BUG_ON(xa, !xa_empty(xa)); - /* But xa_insert does not */ + /* xa_insert treats it as busy */ XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0); XA_BUG_ON(xa, xa_insert(xa, 12345678, xa_mk_value(12345678), 0) != -EBUSY); @@ -398,9 +399,27 @@ static noinline void check_reserve(struct xarray *xa) XA_BUG_ON(xa, xa_reserve(xa, 6, GFP_KERNEL) != 0); xa_store_index(xa, 7, GFP_KERNEL); + count = 0; xa_for_each(xa, index, entry) { XA_BUG_ON(xa, index != 5 && index != 7); + count++; + } + XA_BUG_ON(xa, count != 2); + + /* If we free a reserved entry, we should be able to allocate it */ + if (xa->xa_flags & XA_FLAGS_ALLOC) { + u32 id; + + XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_value(8), + XA_LIMIT(5, 10), GFP_KERNEL) != 0); + XA_BUG_ON(xa, id != 8); + + xa_release(xa, 6); + XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_value(6), + XA_LIMIT(5, 10), GFP_KERNEL) != 0); + XA_BUG_ON(xa, id != 6); } + xa_destroy(xa); } @@ -1486,6 +1505,7 @@ static int xarray_checks(void) check_xas_erase(&array); check_cmpxchg(&array); check_reserve(&array); + check_reserve(&xa0); check_multi_store(&array); check_xa_alloc(); check_find(&array); -- cgit v1.2.3