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Commit 4017dbdc authored by Ben Hutchings's avatar Ben Hutchings
Browse files

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: default avatarBen Hutchings <bhutchings@solarflare.com>
parent 22c8c934

drivers/net/sfc/filter.c

+24 −17
Original line number Diff line number Diff line
@@ -335,30 +335,37 @@ 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 = (filter_idx + incr) & (table->size - 1);

	}

	if (!for_insert)

		return -ENOENT;

	if (depth > depth_max)

		return -EBUSY;

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;

	}

}



/* Construct/deconstruct external filter IDs */



static inline int