Description of problem (https://bugzilla.redhat.com/show_bug.cgi?id=1465735): Run `kdumpctl status` as normal user, get below error messages:
Another app is currently holding the kdump lock; waiting for it to exit... flock: 9: Bad file descriptor Another app is currently holding the kdump lock; waiting for it to exit... flock: 9: Bad file descriptor ...
The bug is caused by behavior difference between bash and sh (bash in posix).
In the function single_instance_lock in kdumpctl script, there is
exec 9>/var/lock/kdump
which will fail in user mode. However, this fail will cause script exiting under bash but not exiting under sh, causing infinite loop because the flock will always fail.
According to the 16th item in ftp://ftp.gnu.org/old-gnu/Manuals/bash-2.02/html_node/bashref_66.html
If a POSIX.2 special builtin returns an error status, a non- interactive shell exits.
And according to https://www.gnu.org/software/bash/manual/html_node/Special-Builtins.html
exec is one of the POSIX.2 special builtin's.
This patch fixes the bug by checking exec return value.
Signed-off-by: Ziyue Yang ziyang@redhat.com --- kdumpctl | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kdumpctl b/kdumpctl index e440bbb..1b50966 100755 --- a/kdumpctl +++ b/kdumpctl @@ -37,6 +37,10 @@ single_instance_lock() local rc timeout=5
exec 9>/var/lock/kdump + if [ $? -ne 0 ]; then + echo "Create file lock failed" + exit 1 + fi
flock -n 9 rc=$?
On 07/12/17 at 10:59am, Ziyue Yang wrote:
Description of problem (https://bugzilla.redhat.com/show_bug.cgi?id=1465735): Run `kdumpctl status` as normal user, get below error messages:
Another app is currently holding the kdump lock; waiting for it to exit... flock: 9: Bad file descriptor Another app is currently holding the kdump lock; waiting for it to exit... flock: 9: Bad file descriptor ...
The bug is caused by behavior difference between bash and sh (bash in posix).
In the function single_instance_lock in kdumpctl script, there is
exec 9>/var/lock/kdump
which will fail in user mode. However, this fail will cause script exiting under bash but not exiting under sh, causing infinite loop because the flock will always fail.
According to the 16th item in ftp://ftp.gnu.org/old-gnu/Manuals/bash-2.02/html_node/bashref_66.html
If a POSIX.2 special builtin returns an error status, a non- interactive shell exits.
And according to https://www.gnu.org/software/bash/manual/html_node/Special-Builtins.html
exec is one of the POSIX.2 special builtin's.
This patch fixes the bug by checking exec return value.
Signed-off-by: Ziyue Yang ziyang@redhat.com
kdumpctl | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kdumpctl b/kdumpctl index e440bbb..1b50966 100755 --- a/kdumpctl +++ b/kdumpctl @@ -37,6 +37,10 @@ single_instance_lock() local rc timeout=5
exec 9>/var/lock/kdump
if [ $? -ne 0 ]; then
echo "Create file lock failed"exit 1fi
flock -n 9 rc=$?
-- 2.9.3 _______________________________________________ kexec mailing list -- kexec@lists.fedoraproject.org To unsubscribe send an email to kexec-leave@lists.fedoraproject.org
Acked-by: Dave Young dyoung@redhat.com
Will add "Fixes: 9fb2996d05c2" when applying it.
Thanks Dave
On 07/13/2017 at 10:33 AM, Dave Young wrote:
On 07/12/17 at 10:59am, Ziyue Yang wrote:
Description of problem (https://bugzilla.redhat.com/show_bug.cgi?id=1465735): Run `kdumpctl status` as normal user, get below error messages:
Another app is currently holding the kdump lock; waiting for it to exit... flock: 9: Bad file descriptor Another app is currently holding the kdump lock; waiting for it to exit... flock: 9: Bad file descriptor ...
The bug is caused by behavior difference between bash and sh (bash in posix).
In the function single_instance_lock in kdumpctl script, there is
exec 9>/var/lock/kdump
which will fail in user mode. However, this fail will cause script exiting under bash but not exiting under sh, causing infinite loop because the flock will always fail.
According to the 16th item in ftp://ftp.gnu.org/old-gnu/Manuals/bash-2.02/html_node/bashref_66.html
If a POSIX.2 special builtin returns an error status, a non- interactive shell exits.
And according to https://www.gnu.org/software/bash/manual/html_node/Special-Builtins.html
exec is one of the POSIX.2 special builtin's.
This patch fixes the bug by checking exec return value.
Signed-off-by: Ziyue Yang ziyang@redhat.com
kdumpctl | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kdumpctl b/kdumpctl index e440bbb..1b50966 100755 --- a/kdumpctl +++ b/kdumpctl @@ -37,6 +37,10 @@ single_instance_lock() local rc timeout=5
exec 9>/var/lock/kdump
if [ $? -ne 0 ]; then
echo "Create file lock failed"exit 1fi
flock -n 9 rc=$?
-- 2.9.3 _______________________________________________ kexec mailing list -- kexec@lists.fedoraproject.org To unsubscribe send an email to kexec-leave@lists.fedoraproject.org
Acked-by: Dave Young dyoung@redhat.com
Will add "Fixes: 9fb2996d05c2" when applying it.
Reviewed-by: Xunlei Pang xlpang@redhat.com
-
Dave Young -
Xunlei Pang -
Ziyue Yang