From 4017dbdc14af1903dc9fcba4d08b89c02325069d Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Fri, 24 Jun 2011 20:26:44 +0100 Subject: sfc: Fix loop condition for efx_filter_search() when !for_insert efx_filter_remove_filter() fails to remove inserted filters in some cases. For example: 1. Two filters A and B have specifications that result in an initial hash collision. 2. A is inserted first, followed by B. 3. An attempt to remove B first succeeds, but if A is removed first a subsequent attempt to remove B fails. When searching for an existing filter (!for_insert), efx_filter_search() must always continue to the maximum search depth for the given type rather than stopping at the first unused entry. Signed-off-by: Ben Hutchings --- drivers/net/sfc/filter.c | 41 ++++++++++++++++++++++++----------------- 1 file changed, 24 insertions(+), 17 deletions(-) (limited to 'drivers/net/sfc') diff --git a/drivers/net/sfc/filter.c b/drivers/net/sfc/filter.c index f2fc2587c09d..054f0a3d45a9 100644 --- a/drivers/net/sfc/filter.c +++ b/drivers/net/sfc/filter.c @@ -335,28 +335,35 @@ static int efx_filter_search(struct efx_filter_table *table, bool for_insert, int *depth_required) { unsigned hash, incr, filter_idx, depth, depth_max; - struct efx_filter_spec *cmp; hash = efx_filter_hash(key); incr = efx_filter_increment(key); - depth_max = (spec->priority <= EFX_FILTER_PRI_HINT ? - FILTER_CTL_SRCH_HINT_MAX : FILTER_CTL_SRCH_MAX); - - for (depth = 1, filter_idx = hash & (table->size - 1); - depth <= depth_max && test_bit(filter_idx, table->used_bitmap); - ++depth) { - cmp = &table->spec[filter_idx]; - if (efx_filter_equal(spec, cmp)) - goto found; + + filter_idx = hash & (table->size - 1); + depth = 1; + depth_max = (for_insert ? + (spec->priority <= EFX_FILTER_PRI_HINT ? + FILTER_CTL_SRCH_HINT_MAX : FILTER_CTL_SRCH_MAX) : + table->search_depth[spec->type]); + + for (;;) { + /* Return success if entry is used and matches this spec + * or entry is unused and we are trying to insert. + */ + if (test_bit(filter_idx, table->used_bitmap) ? + efx_filter_equal(spec, &table->spec[filter_idx]) : + for_insert) { + *depth_required = depth; + return filter_idx; + } + + /* Return failure if we reached the maximum search depth */ + if (depth == depth_max) + return for_insert ? -EBUSY : -ENOENT; + filter_idx = (filter_idx + incr) & (table->size - 1); + ++depth; } - if (!for_insert) - return -ENOENT; - if (depth > depth_max) - return -EBUSY; -found: - *depth_required = depth; - return filter_idx; } /* Construct/deconstruct external filter IDs */ -- cgit v1.2.3-59-g8ed1b