linux-kernel - [PATCH] staging: comedi: avoid using timeval

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Message-Id: <20160617195640.1956208-1-arnd@arndb.de>
Date:	Fri, 17 Jun 2016 21:56:15 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	y2038@...ts.linaro.org, Arnd Bergmann <arnd@...db.de>,
	Ian Abbott <abbotti@....co.uk>,
	H Hartley Sweeten <hsweeten@...ionengravers.com>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: [PATCH] staging: comedi: avoid using timeval

Comedi uses 32-bit seconds for its timestamps, on both 32-bit and
64-bit machines. For all I can tell, this was originally meant as
a 'timespec', which would overflow in 2038 because of the use of
a signed 'long' on 32-bit machines, but it is now used as an
array of two unsigned 'lsampl_t' values in comedilib, which will
only overflow in 2106, on both 32-bit and 64-bit machines.

In an effort to get rid of all uses of 'struct timeval' in the kernel,
this replaces the internal code with a call to ktime_get_real_ts64()
and a comment at the location of the conversion.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/staging/comedi/comedi_fops.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 629080f39db0..10a8a9245925 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -1256,16 +1256,17 @@ static int parse_insn(struct comedi_device *dev, struct comedi_insn *insn,
 		switch (insn->insn) {
 		case INSN_GTOD:
 			{
-				struct timeval tv;
+				struct timespec64 tv;
 
 				if (insn->n != 2) {
 					ret = -EINVAL;
 					break;
 				}
 
-				do_gettimeofday(&tv);
-				data[0] = tv.tv_sec;
-				data[1] = tv.tv_usec;
+				ktime_get_real_ts64(&tv);
+				/* unsigned data safe until 2106 */
+				data[0] = (unsigned int)tv.tv_sec;
+				data[1] = tv.tv_nsec / NSEC_PER_USEC;
 				ret = 2;
 
 				break;
-- 
2.9.0