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i40e: fix i40e_ptp_adjtime when given a negative delta 

Commit 0ac30ce433 ("i40e: fix up 32 bit timespec references",
2017-07-26) claims to be cleaning up references to 32-bit timespecs.

The actual contents of the commit make no sense, as it converts a call
to timespec64_add into timespec64_add_ns. This would seem ok, if (a) the
change was documented in the commit message, and (b) timespec64_add_ns
supported negative numbers.

timespec64_add_ns doesn't work with signed deltas, because the
implementation is based around iter_div_u64_rem. This change resulted in
a regression where i40e_ptp_adjtime would interpret small negative
adjustments as large positive additions, resulting in incorrect
behavior.

This commit doesn't appear to fix anything, is not well explained, and
introduces a bug, so lets just revert it.

Reverts: 0ac30ce433 ("i40e: fix up 32 bit timespec references", 2017-07-26)
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Jacob Keller 2019-02-25 11:20:05 -08:00 committed by Jeff Kirsher
parent 8c838f53e1
commit b3ccbbce1e
1 changed files with 3 additions and 2 deletions
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5
drivers/net/ethernet/intel/i40e/i40e_ptp.c
View File

@ -146,12 +146,13 @@ static int i40e_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
static int i40e_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
struct i40e_pf *pf = container_of(ptp, struct i40e_pf, ptp_caps);
struct timespec64 now;
struct timespec64 now, then;
then = ns_to_timespec64(delta);
mutex_lock(&pf->tmreg_lock);
i40e_ptp_read(pf, &now, NULL);
timespec64_add_ns(&now, delta);
now = timespec64_add(now, then);
i40e_ptp_write(pf, (const struct timespec64 *)&now);
mutex_unlock(&pf->tmreg_lock);