> -----Original Message----- > From: Gaëtan Rivet [mailto:gaetan.ri...@6wind.com] > Sent: Thursday, November 22, 2018 10:54 AM > To: Stojaczyk, Dariusz <dariusz.stojac...@intel.com> > Cc: dev@dpdk.org; tho...@monjalon.net > Subject: Re: [PATCH v2] dev: don't remove devargs that are still referenced > > On Wed, Nov 21, 2018 at 08:38:27PM +0100, Darek Stojaczyk wrote: > > Even if a device failed to plug, it's still a device > > object that references the devargs. Those devargs will > > be freed automatically together with the device, but > > freeing them any earlier - like it's done in the hotplug > > error handling path right now - will give us a dangling > > pointer and a segfault scenario. > > > > Consider the following case: > > * secondary process receives the hotplug request IPC message > > * devargs are either created or updated > > * the bus is scanned > > * a new device object is created with the latest devargs > > * the device can't be plugged for whatever reason, > > bus->plug returns error > > * the devargs are freed, even though they're still referenced > > by the device object on the bus > > > > For PCI devices, the generic device name comes from > > a buffer within the devargs. Freeing those will make > > EAL segfault whenever the device name is checked. > > > > This patch just prevents the hotplug error handling > > path from removing the devargs when there's a device > > that references them. This is done by simply exiting > > early from the hotplug function. As mentioned in the > > beginning, those devargs will be freed later, together > > with the device itself. > > > > This seems ok in conjunction with Thomas' patch on overwriting devargs > on insertion. > > The only place a device will be freed is the unplug bus ops, it already > does remove the device devargs. > > > Fixes: 7e8b26650146 ("eal: fix hotplug add / remove") > > Cc: gaetan.ri...@6wind.com > > Cc: tho...@monjalon.net > > > > Signed-off-by: Darek Stojaczyk <dariusz.stojac...@intel.com> > > --- > > lib/librte_eal/common/eal_common_dev.c | 9 ++++----- > > 1 file changed, 4 insertions(+), 5 deletions(-) > > > > diff --git a/lib/librte_eal/common/eal_common_dev.c > b/lib/librte_eal/common/eal_common_dev.c > > index 1fdc9ab17..b6fc5e437 100644 > > --- a/lib/librte_eal/common/eal_common_dev.c > > +++ b/lib/librte_eal/common/eal_common_dev.c > > @@ -169,11 +169,10 @@ local_dev_probe(const char *devargs, struct > rte_device **new_dev) > > > > ret = dev->bus->plug(dev); > > if (ret) { > > - if (rte_dev_is_probed(dev)) /* if already succeeded earlier > */ > > - return ret; /* no rollback */ > > - RTE_LOG(ERR, EAL, "Driver cannot attach the device (%s)\n", > > - dev->name); > > - goto err_devarg; > > + if (!rte_dev_is_probed(dev)) /* if hasn't succeeded earlier */ > > + RTE_LOG(ERR, EAL, "Driver cannot attach the device > (%s)\n", > > + dev->name); > > Maybe a comment here to describe that the devargs is still the > responsibility of the rte_device and should not be removed.
Ack, I'll do that. > > > + return ret; > > } > > > > *new_dev = dev; > > -- > > 2.17.1 > > > > -- > Gaëtan Rivet > 6WIND
