Why do you need the ID to increment like this? Why can't you just use a unique ID?
> -----Original Message----- > From: Hans Westgaard Ry [mailto:hans.westgaard...@oracle.com] > Sent: Thursday, June 7, 2018 7:15 AM > To: Doug Ledford <dledf...@redhat.com>; Jason Gunthorpe <j...@ziepe.ca>; > Hakon Bugge <haakon.bu...@oracle.com>; Parav Pandit > <pa...@mellanox.com>; Jack Morgenstein <ja...@dev.mellanox.co.il>; Pravin > Shedge <pravin.shedge4li...@gmail.com>; Matthew Wilcox > <mawil...@microsoft.com>; Andrew Morton <a...@linux-foundation.org>; > Jeff Layton <jlay...@kernel.org>; Wei Wang <wei.w.w...@intel.com>; Chris > Mi <chr...@mellanox.com>; Eric Biggers <ebigg...@google.com>; Rasmus > Villemoes <li...@rasmusvillemoes.dk>; Mel Gorman > <mgor...@techsingularity.net>; linux-r...@vger.kernel.org; linux- > ker...@vger.kernel.org > Subject: [PATCH v3 2/2] IB/mad: Use ID allocator routines to allocate agent > number > > The agent TID is a 64 bit value split in two dwords. The least > significant dword is the TID running counter. The most significant > dword is the agent number. In the CX-3 shared port model, the mlx4 > driver uses the most significant byte of the agent number to store the > slave number, making agent numbers greater and equal to 2^24 (3 bytes) > unusable. The current codebase uses a variable which is incremented > atomically for each new agent number giving too large agent numbers > over time. The IDA set of functions are used instead of the simple > counter approach. This allows re-use of agent numbers. > > The signature of the bug is a MAD layer that stops working and the > console is flooded with messages like: > mlx4_ib: egress mad has non-null tid msb:1 class:4 slave:0 > > Signed-off-by: Hans Westgaard Ry <hans.westgaard...@oracle.com> > --- > drivers/infiniband/core/mad.c | 25 +++++++++++++++++++++---- > 1 file changed, 21 insertions(+), 4 deletions(-) > > diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c > index b28452a55a08..c01a2d63ffa2 100644 > --- a/drivers/infiniband/core/mad.c > +++ b/drivers/infiniband/core/mad.c > @@ -41,6 +41,7 @@ > #include <linux/slab.h> > #include <linux/module.h> > #include <linux/security.h> > +#include <linux/idr.h> > #include <rdma/ib_cache.h> > > #include "mad_priv.h" > @@ -59,8 +60,7 @@ 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 struct list_head ib_mad_port_list; > -static atomic_t ib_mad_client_id = ATOMIC_INIT(0); > - > +static DEFINE_IDA(ib_mad_client_ids); > /* Port list lock */ > static DEFINE_SPINLOCK(ib_mad_port_list_lock); > > @@ -212,7 +212,7 @@ struct ib_mad_agent *ib_register_mad_agent(struct > ib_device *device, > int ret2, qpn; > unsigned long flags; > u8 mgmt_class, vclass; > - > + u32 ib_mad_client_id; > /* Validate parameters */ > qpn = get_spl_qp_index(qp_type); > if (qpn == -1) { > @@ -375,9 +375,19 @@ struct ib_mad_agent *ib_register_mad_agent(struct > ib_device *device, > ret = ERR_PTR(ret2); > goto error4; > } > + ib_mad_client_id = ida_simple_get_cyclic(&ib_mad_client_ids, > + 1, > + BIT(24) - 1, > + GFP_KERNEL); > + if (ib_mad_client_id < 0) { > + pr_err("Couldn't allocate agent tid; errcode: %#x\n", > + ib_mad_client_id); > + ret = ERR_PTR(ib_mad_client_id); > + goto error4; > + } > + mad_agent_priv->agent.hi_tid = ib_mad_client_id; > > spin_lock_irqsave(&port_priv->reg_lock, flags); > - mad_agent_priv->agent.hi_tid = > atomic_inc_return(&ib_mad_client_id); > > /* > * Make sure MAD registration (if supplied) > @@ -428,6 +438,8 @@ struct ib_mad_agent *ib_register_mad_agent(struct > ib_device *device, > error5: > spin_unlock_irqrestore(&port_priv->reg_lock, flags); > ib_mad_agent_security_cleanup(&mad_agent_priv->agent); > + ida_simple_remove(&ib_mad_client_ids, ib_mad_client_id); > + > error4: > kfree(reg_req); > error3: > @@ -576,6 +588,7 @@ static void unregister_mad_agent(struct > ib_mad_agent_private *mad_agent_priv) > { > struct ib_mad_port_private *port_priv; > unsigned long flags; > + u32 ib_mad_client_id; > > /* Note that we could still be handling received MADs */ > > @@ -587,6 +600,8 @@ static void unregister_mad_agent(struct > ib_mad_agent_private *mad_agent_priv) > port_priv = mad_agent_priv->qp_info->port_priv; > cancel_delayed_work(&mad_agent_priv->timed_work); > > + ib_mad_client_id = mad_agent_priv->agent.hi_tid; > + > spin_lock_irqsave(&port_priv->reg_lock, flags); > remove_mad_reg_req(mad_agent_priv); > list_del(&mad_agent_priv->agent_list); > @@ -602,6 +617,7 @@ static void unregister_mad_agent(struct > ib_mad_agent_private *mad_agent_priv) > > kfree(mad_agent_priv->reg_req); > kfree(mad_agent_priv); > + ida_simple_remove(&ib_mad_client_ids, ib_mad_client_id); > } > > static void unregister_mad_snoop(struct ib_mad_snoop_private > *mad_snoop_priv) > @@ -3347,4 +3363,5 @@ int ib_mad_init(void) > void ib_mad_cleanup(void) > { > ib_unregister_client(&mad_client); > + ida_destroy(&ib_mad_client_ids); > } > -- > 2.14.3
