Messages in this thread | | | Date | Mon, 24 Sep 2018 00:05:42 -0700 (PDT) | From | Manish Kumar Singh <> | Subject | RE: [PATCH] bonding: avoid repeated display of same link status change |
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> -----Original Message----- > From: Eric Dumazet [mailto:eric.dumazet@gmail.com] > Sent: 18 सितम्बर 2018 19:30 > To: Manish Kumar Singh; Eric Dumazet; netdev@vger.kernel.org > Cc: Jay Vosburgh; Veaceslav Falico; Andy Gospodarek; David S. Miller; linux- > kernel@vger.kernel.org > Subject: Re: [PATCH] bonding: avoid repeated display of same link status > change > > > > On 09/17/2018 10:05 PM, Manish Kumar Singh wrote: > > > > > >> -----Original Message----- > >> From: Eric Dumazet [mailto:eric.dumazet@gmail.com] > >> Sent: 17 सितम्बर 2018 20:08 > >> To: Manish Kumar Singh; netdev@vger.kernel.org > >> Cc: Jay Vosburgh; Veaceslav Falico; Andy Gospodarek; David S. Miller; > linux- > >> kernel@vger.kernel.org > >> Subject: Re: [PATCH] bonding: avoid repeated display of same link status > >> change > >> > >> > >> > >> On 09/17/2018 12:20 AM, mk.singh@oracle.com wrote: > >>> From: Manish Kumar Singh <mk.singh@oracle.com> > >>> > >>> When link status change needs to be committed and rtnl lock couldn't be > >>> taken, avoid redisplay of same link status change message. > >>> > >>> Signed-off-by: Manish Kumar Singh <mk.singh@oracle.com> > >>> --- > >>> drivers/net/bonding/bond_main.c | 6 ++++-- > >>> include/net/bonding.h | 1 + > >>> 2 files changed, 5 insertions(+), 2 deletions(-) > >>> > >>> diff --git a/drivers/net/bonding/bond_main.c > >> b/drivers/net/bonding/bond_main.c > >>> index 217b790d22ed..fb4e3aff1677 100644 > >>> --- a/drivers/net/bonding/bond_main.c > >>> +++ b/drivers/net/bonding/bond_main.c > >>> @@ -2087,7 +2087,7 @@ static int bond_miimon_inspect(struct bonding > >> *bond) > >>> bond_propose_link_state(slave, BOND_LINK_FAIL); > >>> commit++; > >>> slave->delay = bond->params.downdelay; > >>> - if (slave->delay) { > >>> + if (slave->delay && !bond->rtnl_needed) { > >>> netdev_info(bond->dev, "link status down > for > >> %sinterface %s, disabling it in %d ms\n", > >>> (BOND_MODE(bond) == > >>> BOND_MODE_ACTIVEBACKUP) ? > >>> @@ -2127,7 +2127,7 @@ static int bond_miimon_inspect(struct bonding > >> *bond) > >>> commit++; > >>> slave->delay = bond->params.updelay; > >>> > >>> - if (slave->delay) { > >>> + if (slave->delay && !bond->rtnl_needed) { > >>> netdev_info(bond->dev, "link status up for > >> interface %s, enabling it in %d ms\n", > >>> slave->dev->name, > >>> ignore_updelay ? 0 : > >>> @@ -2301,9 +2301,11 @@ static void bond_mii_monitor(struct > >> work_struct *work) > >>> if (!rtnl_trylock()) { > >>> delay = 1; > >>> should_notify_peers = false; > >>> + bond->rtnl_needed = true; > >> > >> How can you set a shared variable with no synchronization ? > > Thanks Eric for reviewing the patch. rtnl_needed is not a shared variable, it > is part of bonding structure, that is one per bonding driver instance. There > can't be two parallel instances of bond_miimon_inspect for a single bonding > driver instance at any given point of time. and only bond_miimon_inspect > updates it. That’s why I think there is no need of any synchronization here. > > > > > > If rtnl_trylock() can not grab RTNL, > there is no way the current thread can set the variable without a race, if the > word including rtnl_needed is shared by other fields in the structure. > > Your patch adds a subtle possibility of future bugs, even if it runs fine today. > > Do not pave the way for future bugs, make your code robust, please.
Thankyou Eric, we are making the changes and will repost the patch after testing it. -Manish > > > > > > >
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