On Fri, Mar 13, 2026 at 04:52:30PM +0100, Greg Kroah-Hartman wrote:
On Fri, Mar 13, 2026 at 11:09:16AM -0400, Sasha Levin wrote:
+ * notes: This syscall has subtle non-POSIX semantics: the fd is ALWAYS closed
+ * regardless of the return value. POSIX specifies that on EINTR, the state
+ * of the fd is unspecified, but Linux always closes it. HP-UX requires
+ * retrying close() on EINTR, but doing so on Linux may close an unrelated
+ * fd that was reassigned by another thread. For portable code, the safest
+ * approach is to check for errors but never retry close().
We don't care about HP-UX :)
Fair :) The original text was contrasting Linux's "always closed" behavior
with HP-UX. I'll just drop that reference.
+ * Error codes from the flush callback (EIO, ENOSPC, EDQUOT) indicate that
+ * previously written data may have been lost. These errors are particularly
+ * common on NFS where write errors are often deferred to close time.
What flush callback?
This was referring to f_op->flush, which filp_flush() calls during close.
But you're right, that's internal plumbing. I'll reworded to describe the
behavior without referencing internal callbacks:
Error codes like EIO, ENOSPC, and EDQUOT indicate that previously
buffered writes may have failed to reach storage.
+ *
+ * The driver's release() callback errors are explicitly ignored by the
+ * kernel, so device driver cleanup errors are not propagated to userspace.
What "The driver" here? release() callbacks aren't really relevant
here.
The original text was noting that __fput() ignores the return value of
f_op->release(), so even if a driver's cleanup fails, userspace never
sees it via close(). But agreed, that's an internal implementation detail
not relevant to the syscall specification. Removed.
Thanks for the review!
--
Thanks,
Sasha
