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Cygwin: timerfd: fix shared memory allocation in fork/exec 

timerfd_tracker::fixup_after_fork_exec always tries to restore
the shared timer region at the same address as in the parent.
This is entirely unnecessary and wasn't intended, rather some
kind of copy/paste thinko.  Fix that.  Print NtMapViewOfSection
status code in api_fatal on failure for debugging.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2019-02-24 20:15:36 +01:00
parent aeaa051f3b
commit a4e2eb6ba3
2 changed files with 11 additions and 6 deletions
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3
winsup/cygwin/release/3.0.2
View File

@ -12,6 +12,9 @@ Bug Fixes
- Fix timerfd select always returning immediately.
Addresses: https://cygwin.com/ml/cygwin/2019-02/msg00364.html
- Fix fork/exec failing to restore timerfd share mem in child process.
Addresses: https://cygwin.com/ml/cygwin/2019-02/msg00400.html
- Drop enforcing case-correct group names for AD accounts to avoid
excessively long startup times.
Addresses: https://cygwin.com/ml/cygwin/2019-02/msg00301.html

14
winsup/cygwin/timerfd.cc
View File

@ -408,6 +408,7 @@ void
timerfd_tracker::fixup_after_fork_exec (bool execing)
{
NTSTATUS status;
PVOID base_address = NULL;
OBJECT_ATTRIBUTES attr;
SIZE_T vsize = PAGE_SIZE;
@ -416,11 +417,12 @@ timerfd_tracker::fixup_after_fork_exec (bool execing)
return;
/* Recreate shared section mapping */
status = NtMapViewOfSection (tfd_shared_hdl, NtCurrentProcess (),
(void **) &tfd_shared, 0, PAGE_SIZE, NULL,
&vsize, ViewShare, MEM_TOP_DOWN, PAGE_READWRITE);
&base_address, 0, PAGE_SIZE, NULL,
&vsize, ViewShare, 0, PAGE_READWRITE);
if (!NT_SUCCESS (status))
api_fatal ("Can't recreate shared timerfd section during %s!",
execing ? "execve" : "fork");
api_fatal ("Can't recreate shared timerfd section during %s, status %y!",
execing ? "execve" : "fork", status);
tfd_shared = (timerfd_shared *) base_address;
/* Increment global instance count by the number of instances in this
process */
InterlockedAdd (&tfd_shared->instance_count, local_instance_count);
@ -430,8 +432,8 @@ timerfd_tracker::fixup_after_fork_exec (bool execing)
status = NtCreateEvent (&cancel_evt, EVENT_ALL_ACCESS, &attr,
NotificationEvent, FALSE);
if (!NT_SUCCESS (status))
api_fatal ("Can't recreate timerfd cancel event during %s!",
execing ? "execve" : "fork");
api_fatal ("Can't recreate timerfd cancel event during %s, status %y!",
execing ? "execve" : "fork", status);
/* Set winpid so we don't run this twice */
winpid = GetCurrentProcessId ();
new cygthread (timerfd_thread, this, "timerfd", sync_thr);