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Fix bug in bitsequence.pushReservation

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- pushReservation fails to correctly detect when
  the affected block is the last in the current
  sequence. It thinks instead the block is in between
  the sequence. Because of this a couple of issues
  may happen:
   1. The allocation of the last bit causes the creation
      of a phantom sequence (length 0) at the end.
      (This has no side effects).
   2. The allocation of a bit somewhere in the middle of
      the bitmask may lead to a completely incorrect
      sequence pattern.

Signed-off-by: Alessandro Boch <aboch@docker.com>
This commit is contained in:
Alessandro Boch 2015-11-23 21:34:16 -08:00
parent 8b079865c7
commit 90711b0def
2 changed files with 112 additions and 1 deletions
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2
libnetwork/bitseq/sequence.go
View file

@ -552,7 +552,7 @@ func pushReservation(bytePos, bitPos uint64, head *sequence, release bool) *sequ
}
removeCurrentIfEmpty(&newHead, newSequence, current)
mergeSequences(previous)
} else if precBlocks == current.count-2 { // Last in sequence (B)
} else if precBlocks == current.count { // Last in sequence (B)
newSequence.next = current.next
current.next = newSequence
mergeSequences(current)

111
libnetwork/bitseq/sequence_test.go
View file

@ -352,6 +352,62 @@ func TestPushReservation(t *testing.T) {
{&sequence{block: 0xffff0000, count: 7}, 25, 7, &sequence{block: 0xffff0000, count: 7}},
{&sequence{block: 0xffffffff, count: 7, next: &sequence{block: 0xfffffffe, count: 1, next: &sequence{block: 0xffffffff, count: 1}}}, 7, 7,
&sequence{block: 0xffffffff, count: 7, next: &sequence{block: 0xfffffffe, count: 1, next: &sequence{block: 0xffffffff, count: 1}}}},
// Set last bit
{&sequence{block: 0x0, count: 8}, 31, 7, &sequence{block: 0x0, count: 7, next: &sequence{block: 0x1, count: 1}}},
// Set bit in a middle sequence in the first block, first bit
{&sequence{block: 0x40000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 4, 0,
&sequence{block: 0x40000000, count: 1, next: &sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 5,
next: &sequence{block: 0x1, count: 1}}}}},
// Set bit in a middle sequence in the first block, first bit (merge involved)
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 4, 0,
&sequence{block: 0x80000000, count: 2, next: &sequence{block: 0x0, count: 5, next: &sequence{block: 0x1, count: 1}}}},
// Set bit in a middle sequence in the first block, last bit
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 4, 31,
&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x1, count: 1, next: &sequence{block: 0x0, count: 5,
next: &sequence{block: 0x1, count: 1}}}}},
// Set bit in a middle sequence in the first block, middle bit
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 4, 16,
&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x8000, count: 1, next: &sequence{block: 0x0, count: 5,
next: &sequence{block: 0x1, count: 1}}}}},
// Set bit in a middle sequence in a middle block, first bit
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 16, 0,
&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 3, next: &sequence{block: 0x80000000, count: 1,
next: &sequence{block: 0x0, count: 2, next: &sequence{block: 0x1, count: 1}}}}}},
// Set bit in a middle sequence in a middle block, last bit
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 16, 31,
&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 3, next: &sequence{block: 0x1, count: 1,
next: &sequence{block: 0x0, count: 2, next: &sequence{block: 0x1, count: 1}}}}}},
// Set bit in a middle sequence in a middle block, middle bit
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 16, 15,
&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 3, next: &sequence{block: 0x10000, count: 1,
next: &sequence{block: 0x0, count: 2, next: &sequence{block: 0x1, count: 1}}}}}},
// Set bit in a middle sequence in the last block, first bit
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 24, 0,
&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 5, next: &sequence{block: 0x80000000, count: 1,
next: &sequence{block: 0x1, count: 1}}}}},
// Set bit in a middle sequence in the last block, last bit
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x4, count: 1}}}, 24, 31,
&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 5, next: &sequence{block: 0x1, count: 1,
next: &sequence{block: 0x4, count: 1}}}}},
// Set bit in a middle sequence in the last block, last bit (merge involved)
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 24, 31,
&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 5, next: &sequence{block: 0x1, count: 2}}}},
// Set bit in a middle sequence in the last block, middle bit
{&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 6, next: &sequence{block: 0x1, count: 1}}}, 24, 16,
&sequence{block: 0x80000000, count: 1, next: &sequence{block: 0x0, count: 5, next: &sequence{block: 0x8000, count: 1,
next: &sequence{block: 0x1, count: 1}}}}},
}
for n, i := range input {
@ -635,3 +691,58 @@ func TestSetInRange(t *testing.T) {
t.Fatalf("Unexpected error: %v", err)
}
}
// This one tests an allocation pattern which unveiled an issue in pushReservation
// Specifically a failure in detecting when we are in the (B) case (the bit to set
// belongs to the last block of the current sequence). Because of a bug, code
// was assuming the bit belonged to a block in the middle of the current sequence.
// Which in turn caused an incorrect allocation when requesting a bit which is not
// in the first or last sequence block.
func TestSetAnyInRange(t *testing.T) {
numBits := uint64(8 * blockLen)
hnd, err := NewHandle("", nil, "", numBits)
if err != nil {
t.Fatal(err)
}
if err := hnd.Set(0); err != nil {
t.Fatal(err)
}
if err := hnd.Set(255); err != nil {
t.Fatal(err)
}
o, err := hnd.SetAnyInRange(128, 255)
if err != nil {
t.Fatal(err)
}
if o != 128 {
t.Fatalf("Unexpected ordinal: %d", o)
}
o, err = hnd.SetAnyInRange(128, 255)
if err != nil {
t.Fatal(err)
}
if o != 129 {
t.Fatalf("Unexpected ordinal: %d", o)
}
o, err = hnd.SetAnyInRange(246, 255)
if err != nil {
t.Fatal(err)
}
if o != 246 {
t.Fatalf("Unexpected ordinal: %d", o)
}
o, err = hnd.SetAnyInRange(246, 255)
if err != nil {
t.Fatal(err)
}
if o != 247 {
t.Fatalf("Unexpected ordinal: %d", o)
}
}