On Fri, Jun 08, 2018 at 10:42:18AM -0700, Matthew Wilcox wrote: > From: Matthew Wilcox <mawil...@microsoft.com> > > Allocate agent IDs from a global IDR instead of an atomic variable. > This eliminates the possibility of reusing an ID which is already in > use after 4 billion registrations, and we can also limit the assigned > ID to be less than 2^24, which fixes a bug in the mlx4 device. > > We look up the agent under protection of the RCU lock, which means we > have to free the agent using kfree_rcu, and only increment the reference > counter if it is not 0. > > Signed-off-by: Matthew Wilcox <mawil...@microsoft.com> > drivers/infiniband/core/mad.c | 78 ++++++++++++++++++------------ > drivers/infiniband/core/mad_priv.h | 7 +-- > include/linux/idr.h | 9 ++++ > 3 files changed, 59 insertions(+), 35 deletions(-) > > diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c > index 68f4dda916c8..62384a3dd3ec 100644 > +++ b/drivers/infiniband/core/mad.c > @@ -38,6 +38,7 @@ > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > #include <linux/dma-mapping.h> > +#include <linux/idr.h> > #include <linux/slab.h> > #include <linux/module.h> > #include <linux/security.h> > @@ -58,8 +59,8 @@ MODULE_PARM_DESC(send_queue_size, "Size of send queue in > number of work requests > module_param_named(recv_queue_size, mad_recvq_size, int, 0444); > MODULE_PARM_DESC(recv_queue_size, "Size of receive queue in number of work > requests"); > > +static DEFINE_IDR(ib_mad_clients); > static struct list_head ib_mad_port_list; > -static atomic_t ib_mad_client_id = ATOMIC_INIT(0); > > /* Port list lock */ > static DEFINE_SPINLOCK(ib_mad_port_list_lock); > @@ -377,13 +378,24 @@ struct ib_mad_agent *ib_register_mad_agent(struct > ib_device *device, > goto error4; > } > > - spin_lock_irq(&port_priv->reg_lock); > - mad_agent_priv->agent.hi_tid = atomic_inc_return(&ib_mad_client_id); > + idr_preload(GFP_KERNEL); > + idr_lock(&ib_mad_clients); > + ret2 = idr_alloc_cyclic(&ib_mad_clients, mad_agent_priv, 0, > + (1 << 24), GFP_ATOMIC);
I like this series, my only concern is this magic number here, at the very least it deserves a big comment explaining why it exists.. Let me see if I can get someone to give it some test time, I assume you haven't been able to test it it? > diff --git a/include/linux/idr.h b/include/linux/idr.h > index e856f4e0ab35..bef0df8600e2 100644 > +++ b/include/linux/idr.h > @@ -81,6 +81,15 @@ static inline void idr_set_cursor(struct idr *idr, > unsigned int val) > WRITE_ONCE(idr->idr_next, val); > } > > +#define idr_lock(idr) xa_lock(&(idr)->idr_rt) > +#define idr_unlock(idr) xa_unlock(&(idr)->idr_rt) > +#define idr_lock_irq(idr) xa_lock_irq(&(idr)->idr_rt) > +#define idr_unlock_irq(idr) xa_unlock_irq(&(idr)->idr_rt) > +#define idr_lock_irqsave(idr, flags) \ > + xa_lock_irqsave(&(idr)->idr_rt, flags) > +#define idr_unlock_irqrestore(idr, flags) \ > + xa_unlock_irqrestore(&(idr)->idr_rt, flags) > + And you are Ok to take these through the rdma tree? Thanks, Jason
