Misbehaving git bisect bad HEAD

Misbehaving git bisect bad HEAD

[Andreas Schwab]

Running "git bisect bad" should be the same as "git bisect bad HEAD",
shouldn't it?

When replaying this bisect log on the Linux kernel tree:

git bisect start
# bad: [97bf6af1f928216fd6c5a66e8a57bfa95a659672] Linux 3.19-rc1
git bisect bad 97bf6af1f928216fd6c5a66e8a57bfa95a659672
# good: [b2776bf7149bddd1f4161f14f79520f17fc1d71d] Linux 3.18
git bisect good b2776bf7149bddd1f4161f14f79520f17fc1d71d
# good: [70e71ca0af244f48a5dcf56dc435243792e3a495] Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
git bisect good 70e71ca0af244f48a5dcf56dc435243792e3a495
# good: [988adfdffdd43cfd841df734664727993076d7cb] Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux
git bisect good 988adfdffdd43cfd841df734664727993076d7cb
# good: [b024793188002b9eed452b5f6a04d45003ed5772] staging: rtl8723au: phy_SsPwrSwitch92CU() was never called with bRegSSPwrLvl != 1
git bisect good b024793188002b9eed452b5f6a04d45003ed5772
# good: [66dcff86ba40eebb5133cccf450878f2bba102ef] Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
git bisect good 66dcff86ba40eebb5133cccf450878f2bba102ef
# bad: [88a57667f2990f00b019d46c8426441c9e516d51] Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect bad 88a57667f2990f00b019d46c8426441c9e516d51
# good: [0ec28c37c21a2b4393692e832e11a7573ac545e2] Merge tag 'media/v3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
git bisect good 0ec28c37c21a2b4393692e832e11a7573ac545e2
# good: [c0f486fde3f353232c1cc2fd4d62783ac782a467] Merge tag 'pm+acpi-3.19-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
git bisect good c0f486fde3f353232c1cc2fd4d62783ac782a467
# bad: [34b85e3574424beb30e4cd163e6da2e2282d2683] Merge tag 'powerpc-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux
git bisect bad 34b85e3574424beb30e4cd163e6da2e2282d2683
# good: [64ec45bff6b3dade2643ed4c0f688a15ecf46ea2] Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
git bisect good 64ec45bff6b3dade2643ed4c0f688a15ecf46ea2

Running "git bisect bad" gives this:

$ git bisect bad 
Bisecting: 6 revisions left to test after this (roughly 3 steps)
[ec2aef5a8d3c14272f7a2d29b34f1f8e71f2be5b] power/perf/hv-24x7: Use kmem_cache_free() instead of kfree

Running "git bisect bad HEAD" instead gives this:

$ git bisect bad HEAD
Bisecting: a merge base must be tested
[56548fc0e86cb9156af7a7e1f15ba78f251dafaf] powerpc/powernv: Return to cpu offline loop when finished in KVM guest

This is git 2.2.1.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: Misbehaving git bisect bad HEAD

[Christian Couder]

On Mon, Dec 22, 2014 at 3:04 PM, Andreas Schwab <schwab@linux-m68k.org> wrote:
> Running "git bisect bad" should be the same as "git bisect bad HEAD",
> shouldn't it?

Yeah, it should.

> When replaying this bisect log on the Linux kernel tree:
>
> git bisect start
> # bad: [97bf6af1f928216fd6c5a66e8a57bfa95a659672] Linux 3.19-rc1
> git bisect bad 97bf6af1f928216fd6c5a66e8a57bfa95a659672
> # good: [b2776bf7149bddd1f4161f14f79520f17fc1d71d] Linux 3.18
> git bisect good b2776bf7149bddd1f4161f14f79520f17fc1d71d
> # good: [70e71ca0af244f48a5dcf56dc435243792e3a495] Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
> git bisect good 70e71ca0af244f48a5dcf56dc435243792e3a495
> # good: [988adfdffdd43cfd841df734664727993076d7cb] Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux
> git bisect good 988adfdffdd43cfd841df734664727993076d7cb
> # good: [b024793188002b9eed452b5f6a04d45003ed5772] staging: rtl8723au: phy_SsPwrSwitch92CU() was never called with bRegSSPwrLvl != 1
> git bisect good b024793188002b9eed452b5f6a04d45003ed5772
> # good: [66dcff86ba40eebb5133cccf450878f2bba102ef] Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
> git bisect good 66dcff86ba40eebb5133cccf450878f2bba102ef
> # bad: [88a57667f2990f00b019d46c8426441c9e516d51] Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
> git bisect bad 88a57667f2990f00b019d46c8426441c9e516d51
> # good: [0ec28c37c21a2b4393692e832e11a7573ac545e2] Merge tag 'media/v3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
> git bisect good 0ec28c37c21a2b4393692e832e11a7573ac545e2
> # good: [c0f486fde3f353232c1cc2fd4d62783ac782a467] Merge tag 'pm+acpi-3.19-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
> git bisect good c0f486fde3f353232c1cc2fd4d62783ac782a467
> # bad: [34b85e3574424beb30e4cd163e6da2e2282d2683] Merge tag 'powerpc-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux
> git bisect bad 34b85e3574424beb30e4cd163e6da2e2282d2683
> # good: [64ec45bff6b3dade2643ed4c0f688a15ecf46ea2] Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
> git bisect good 64ec45bff6b3dade2643ed4c0f688a15ecf46ea2
>
> Running "git bisect bad" gives this:
>
> $ git bisect bad
> Bisecting: 6 revisions left to test after this (roughly 3 steps)
> [ec2aef5a8d3c14272f7a2d29b34f1f8e71f2be5b] power/perf/hv-24x7: Use kmem_cache_free() instead of kfree
>
> Running "git bisect bad HEAD" instead gives this:
>
> $ git bisect bad HEAD
> Bisecting: a merge base must be tested
> [56548fc0e86cb9156af7a7e1f15ba78f251dafaf] powerpc/powernv: Return to cpu offline loop when finished in KVM guest
>
> This is git 2.2.1.

I think it is a very old bug.

The following patch should fix it:

diff --git a/git-bisect.sh b/git-bisect.sh
index 6cda2b5..26a336a 100755
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -200,7 +200,8 @@ is_expected_rev() {

 check_expected_revs() {
        for _rev in "$@"; do
-               if ! is_expected_rev "$_rev"
+               _parsed=$(git rev-parse --verify "$_rev")
+               if ! is_expected_rev "$_parsed"
                then
                        rm -f "$GIT_DIR/BISECT_ANCESTORS_OK"
                        rm -f "$GIT_DIR/BISECT_EXPECTED_REV"

I will send a proper patch later.

Thanks,
Christian.