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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 <bhutchings@solarflare.com>
This commit is contained in:
Ben Hutchings 2011-06-24 20:26:44 +01:00
parent 22c8c93432
commit 4017dbdc14
1 changed files with 23 additions and 16 deletions
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39
drivers/net/sfc/filter.c
View File

@ -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 */