IB/hfi1: Fix an assign/ordering issue with shared context IDs

The current algorithm for generating sub-context IDs is FILO.  If the
contexts are not closed in that order, the uniqueness of the ID will be
compromised. I.e. logging the creation/deletion of context IDs with an
application that assigns and closes in a FIFO order reveals:

cache_id: assign: uctxt: 3    sub_ctxt: 0
cache_id: assign: uctxt: 3    sub_ctxt: 1
cache_id: assign: uctxt: 3    sub_ctxt: 2
cache_id: close:  uctxt: 3    sub_ctxt: 0
cache_id: assign: uctxt: 3    sub_ctxt: 2 <<<

The sub_ctxt ID 2 is reused incorrectly.

Update the sub-context ID assign algorithm to use a bitmask of in_use
contexts.  The new algorithm will allow the contexts to be closed in any
order, and will only re-use unused contexts.

Size subctxt and subctxt_cnt to match the user API size.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

6 files changed, 41 insertions, 28 deletions

diff --git a/drivers/infiniband/hw/hfi1/driver.c b/drivers/infiniband/hw/hfi1/driver.c
index 566d152e36f2..a50870e455a3 100644
--- a/drivers/infiniband/hw/hfi1/driver.c
+++ b/drivers/infiniband/hw/hfi1/driver.c
@@ -1289,7 +1289,7 @@ int hfi1_reset_device(int unit)
         if (dd->rcd)
                 for (i = dd->first_dyn_alloc_ctxt;
                      i < dd->num_rcv_contexts; i++) {
-                        if (!dd->rcd[i] || !dd->rcd[i]->cnt)
+                        if (!dd->rcd[i])
                                 continue;
                         spin_unlock_irqrestore(&dd->uctxt_lock, flags);
                         ret = -EBUSY;
diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c
index 467f876551ba..9c177ef79db5 100644
--- a/drivers/infiniband/hw/hfi1/file_ops.c
+++ b/drivers/infiniband/hw/hfi1/file_ops.c
@@ -49,6 +49,7 @@
 #include <linux/vmalloc.h>
 #include <linux/io.h>
 #include <linux/sched/mm.h>
+#include <linux/bitmap.h>
 
 #include <rdma/ib.h>
 
@@ -95,11 +96,10 @@ static int allocate_ctxt(struct hfi1_filedata *fd, struct hfi1_devdata *dd,
                          struct hfi1_user_info *uinfo);
 static unsigned int poll_urgent(struct file *fp, struct poll_table_struct *pt);
 static unsigned int poll_next(struct file *fp, struct poll_table_struct *pt);
-static int user_event_ack(struct hfi1_ctxtdata *uctxt, int subctxt,
+static int user_event_ack(struct hfi1_ctxtdata *uctxt, u16 subctxt,
                           unsigned long events);
-static int set_ctxt_pkey(struct hfi1_ctxtdata *uctxt, unsigned subctxt,
-                         u16 pkey);
-static int manage_rcvq(struct hfi1_ctxtdata *uctxt, unsigned subctxt,
+static int set_ctxt_pkey(struct hfi1_ctxtdata *uctxt, u16 subctxt, u16 pkey);
+static int manage_rcvq(struct hfi1_ctxtdata *uctxt, u16 subctxt,
                        int start_stop);
 static int vma_fault(struct vm_fault *vmf);
 static long hfi1_file_ioctl(struct file *fp, unsigned int cmd,
@@ -773,8 +773,8 @@ static int hfi1_file_close(struct inode *inode, struct file *fp)
                            HFI1_MAX_SHARED_CTXTS) + fdata->subctxt;
         *ev = 0;
 
-        if (--uctxt->cnt) {
-                uctxt->active_slaves &= ~(1 << fdata->subctxt);
+        __clear_bit(fdata->subctxt, uctxt->in_use_ctxts);
+        if (!bitmap_empty(uctxt->in_use_ctxts, HFI1_MAX_SHARED_CTXTS)) {
                 mutex_unlock(&hfi1_mutex);
                 goto done;
         }
@@ -868,7 +868,7 @@ static int assign_ctxt(struct hfi1_filedata *fd, struct hfi1_user_info *uinfo)
         }
 
         /*
-         * Allocate a base context f context sharing is not required or we
+         * Allocate a base context if context sharing is not required or we
          * couldn't find a sub context.
          */
         if (!ret)
@@ -905,17 +905,24 @@ static int assign_ctxt(struct hfi1_filedata *fd, struct hfi1_user_info *uinfo)
         return ret;
 }
 
+/*
+ * The hfi1_mutex must be held when this function is called.  It is
+ * necessary to ensure serialized access to the bitmask in_use_ctxts.
+ */
 static int find_sub_ctxt(struct hfi1_filedata *fd,
                          const struct hfi1_user_info *uinfo)
 {
         int i;
         struct hfi1_devdata *dd = fd->dd;
+        u16 subctxt;
 
         for (i = dd->first_dyn_alloc_ctxt; i < dd->num_rcv_contexts; i++) {
                 struct hfi1_ctxtdata *uctxt = dd->rcd[i];
 
                 /* Skip ctxts which are not yet open */
-                if (!uctxt || !uctxt->cnt)
+                if (!uctxt ||
+                    bitmap_empty(uctxt->in_use_ctxts,
+                                 HFI1_MAX_SHARED_CTXTS))
                         continue;
 
                 /* Skip dynamically allocted kernel contexts */
@@ -931,13 +938,19 @@ static int find_sub_ctxt(struct hfi1_filedata *fd,
                         continue;
 
                 /* Verify the sharing process matches the master */
-                if (uctxt->userversion != uinfo->userversion ||
-                    uctxt->cnt >= uctxt->subctxt_cnt) {
+                if (uctxt->userversion != uinfo->userversion)
                         return -EINVAL;
-                }
+
+                /* Find an unused context */
+                subctxt = find_first_zero_bit(uctxt->in_use_ctxts,
+                                              HFI1_MAX_SHARED_CTXTS);
+                if (subctxt >= uctxt->subctxt_cnt)
+                        return -EINVAL;
+
                 fd->uctxt = uctxt;
-                fd->subctxt  = uctxt->cnt++;
-                uctxt->active_slaves |= 1 << fd->subctxt;
+                fd->subctxt = subctxt;
+                __set_bit(fd->subctxt, uctxt->in_use_ctxts);
+
                 return 1;
         }
 
@@ -1055,7 +1068,7 @@ ctxdata_free:
 static int init_subctxts(struct hfi1_ctxtdata *uctxt,
                          const struct hfi1_user_info *uinfo)
 {
-        unsigned num_subctxts;
+        u16 num_subctxts;
 
         num_subctxts = uinfo->subctxt_cnt;
         if (num_subctxts > HFI1_MAX_SHARED_CTXTS)
@@ -1063,7 +1076,6 @@ static int init_subctxts(struct hfi1_ctxtdata *uctxt,
 
         uctxt->subctxt_cnt = uinfo->subctxt_cnt;
         uctxt->subctxt_id = uinfo->subctxt_id;
-        uctxt->active_slaves = 1;
         uctxt->redirect_seq_cnt = 1;
         set_bit(HFI1_CTXT_BASE_UNINIT, &uctxt->event_flags);
 
@@ -1073,7 +1085,7 @@ static int init_subctxts(struct hfi1_ctxtdata *uctxt,
 static int setup_subctxt(struct hfi1_ctxtdata *uctxt)
 {
         int ret = 0;
-        unsigned num_subctxts = uctxt->subctxt_cnt;
+        u16 num_subctxts = uctxt->subctxt_cnt;
 
         uctxt->subctxt_uregbase = vmalloc_user(PAGE_SIZE);
         if (!uctxt->subctxt_uregbase)
@@ -1425,7 +1437,7 @@ done:
  * overflow conditions.  start_stop==1 re-enables, to be used to
  * re-init the software copy of the head register
  */
-static int manage_rcvq(struct hfi1_ctxtdata *uctxt, unsigned subctxt,
+static int manage_rcvq(struct hfi1_ctxtdata *uctxt, u16 subctxt,
                        int start_stop)
 {
         struct hfi1_devdata *dd = uctxt->dd;
@@ -1460,7 +1472,7 @@ bail:
  * User process then performs actions appropriate to bit having been
  * set, if desired, and checks again in future.
  */
-static int user_event_ack(struct hfi1_ctxtdata *uctxt, int subctxt,
+static int user_event_ack(struct hfi1_ctxtdata *uctxt, u16 subctxt,
                           unsigned long events)
 {
         int i;
@@ -1481,8 +1493,7 @@ static int user_event_ack(struct hfi1_ctxtdata *uctxt, int subctxt,
         return 0;
 }
 
-static int set_ctxt_pkey(struct hfi1_ctxtdata *uctxt, unsigned subctxt,
-                         u16 pkey)
+static int set_ctxt_pkey(struct hfi1_ctxtdata *uctxt, u16 subctxt, u16 pkey)
 {
         int ret = -ENOENT, i, intable = 0;
         struct hfi1_pportdata *ppd = uctxt->ppd;
diff --git a/drivers/infiniband/hw/hfi1/hfi.h b/drivers/infiniband/hw/hfi1/hfi.h
index 1b7203a3f1ce..f3d75fcd5f07 100644
--- a/drivers/infiniband/hw/hfi1/hfi.h
+++ b/drivers/infiniband/hw/hfi1/hfi.h
@@ -228,7 +228,7 @@ struct hfi1_ctxtdata {
         unsigned ctxt;
         /*
          * non-zero if ctxt can be shared, and defines the maximum number of
-         * sub contexts allowed.
+         * sub-contexts for this device context.
          */
         u16 subctxt_cnt;
         /* non-zero if ctxt is being shared. */
@@ -287,10 +287,10 @@ struct hfi1_ctxtdata {
         void *subctxt_rcvegrbuf;
         /* An array of pages for the eager header queue entries * N */
         void *subctxt_rcvhdr_base;
+        /* Bitmask of in use context(s) */
+        DECLARE_BITMAP(in_use_ctxts, HFI1_MAX_SHARED_CTXTS);
         /* The version of the library which opened this ctxt */
         u32 userversion;
-        /* Bitmask of active slaves */
-        u32 active_slaves;
         /* Type of packets or conditions we want to poll for */
         u16 poll_type;
         /* receive packet sequence counter */
@@ -1239,9 +1239,9 @@ struct mmu_rb_handler;
 struct hfi1_filedata {
         struct hfi1_devdata *dd;
         struct hfi1_ctxtdata *uctxt;
-        unsigned subctxt;
         struct hfi1_user_sdma_comp_q *cq;
         struct hfi1_user_sdma_pkt_q *pq;
+        u16 subctxt;
         /* for cpu affinity; -1 if none */
         int rec_cpu_num;
         u32 tid_n_pinned;
diff --git a/drivers/infiniband/hw/hfi1/init.c b/drivers/infiniband/hw/hfi1/init.c
index 52a6364c30de..694a8ecf9f26 100644
--- a/drivers/infiniband/hw/hfi1/init.c
+++ b/drivers/infiniband/hw/hfi1/init.c
@@ -53,6 +53,7 @@
 #include <linux/module.h>
 #include <linux/printk.h>
 #include <linux/hrtimer.h>
+#include <linux/bitmap.h>
 #include <rdma/rdma_vt.h>
 
 #include "hfi.h"
@@ -222,7 +223,7 @@ struct hfi1_ctxtdata *hfi1_create_ctxtdata(struct hfi1_pportdata *ppd, u32 ctxt,
                 INIT_LIST_HEAD(&rcd->qp_wait_list);
                 rcd->ppd = ppd;
                 rcd->dd = dd;
-                rcd->cnt = 1;
+                __set_bit(0, rcd->in_use_ctxts);
                 rcd->ctxt = ctxt;
                 dd->rcd[ctxt] = rcd;
                 rcd->numa_id = numa;
diff --git a/drivers/infiniband/hw/hfi1/intr.c b/drivers/infiniband/hw/hfi1/intr.c
index 232014d46f79..ba265d0ae93b 100644
--- a/drivers/infiniband/hw/hfi1/intr.c
+++ b/drivers/infiniband/hw/hfi1/intr.c
@@ -47,6 +47,7 @@
 
 #include <linux/pci.h>
 #include <linux/delay.h>
+#include <linux/bitmap.h>
 
 #include "hfi.h"
 #include "common.h"
@@ -189,7 +190,7 @@ void handle_user_interrupt(struct hfi1_ctxtdata *rcd)
         unsigned long flags;
 
         spin_lock_irqsave(&dd->uctxt_lock, flags);
-        if (!rcd->cnt)
+        if (bitmap_empty(rcd->in_use_ctxts, HFI1_MAX_SHARED_CTXTS))
                 goto done;
 
         if (test_and_clear_bit(HFI1_CTXT_WAITING_RCV, &rcd->event_flags)) {
diff --git a/drivers/infiniband/hw/hfi1/user_sdma.h b/drivers/infiniband/hw/hfi1/user_sdma.h
index 9181d7cbe8f6..e5b10aefe212 100644
--- a/drivers/infiniband/hw/hfi1/user_sdma.h
+++ b/drivers/infiniband/hw/hfi1/user_sdma.h
@@ -58,7 +58,7 @@ extern uint extended_psn;
 struct hfi1_user_sdma_pkt_q {
         struct list_head list;
         unsigned ctxt;
-        unsigned subctxt;
+        u16 subctxt;
         u16 n_max_reqs;
         atomic_t n_reqs;
         u16 reqidx;