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RDMA/bnxt_re: Enhance dpi lifecycle logic in doorbell uapis

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If the DPI is freed when the dbr object is freed, but if the
process has not unmapped the page yet, then the DPI slot could
get reallocated to another process while the original process
still has it mapped. To prevent this, save the DPI info in the
mmap entry during dbr allocation and free the DPI slot from
bnxt_re_mmap_free(), which enures that there are no references
to it.

This change is needed to support doorbell allocation to QPs
in the next patch.

Link: https://patch.msgid.link/r/20260519150041.7251-8-sriharsha.basavapatna@broadcom.com
Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Reviewed-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Sriharsha Basavapatna
2026-05-19 20:30:39 +05:30
committed by Jason Gunthorpe
parent 73607410f4
commit 54c01d98f4
3 changed files with 17 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/infiniband/hw/bnxt_re/ib_verbs.c
View File

@@ -4943,6 +4943,10 @@ void bnxt_re_mmap_free(struct rdma_user_mmap_entry *rdma_entry)
bnxt_entry = container_of(rdma_entry, struct bnxt_re_user_mmap_entry,
rdma_entry);
if (bnxt_entry->dpi_valid)
bnxt_qplib_free_uc_dpi(&bnxt_entry->uctx->rdev->qplib_res,
&bnxt_entry->dpi);
kfree(bnxt_entry);
}

2
drivers/infiniband/hw/bnxt_re/ib_verbs.h
View File

@@ -161,6 +161,8 @@ struct bnxt_re_user_mmap_entry {
struct bnxt_re_ucontext *uctx;
u64 mem_offset;
u8 mmap_flag;
bool dpi_valid;
struct bnxt_qplib_dpi dpi;
};
struct bnxt_re_dbr_obj {

13
drivers/infiniband/hw/bnxt_re/uapi.c
View File

@@ -368,6 +368,13 @@ static int UVERBS_HANDLER(BNXT_RE_METHOD_DBR_ALLOC)(struct uverbs_attr_bundle *a
goto free_dpi;
}
/* Save DPI info to the mmap entry so that bnxt_re_mmap_free()
* can free the DPI slot only after the last reference to the
* mmap entry is released.
*/
obj->entry->dpi = *dpi;
obj->entry->dpi_valid = true;
obj->rdev = rdev;
kref_init(&obj->usecnt);
uobj->object = obj;
@@ -396,10 +403,12 @@ void bnxt_re_dbr_kref_release(struct kref *ref)
{
struct bnxt_re_dbr_obj *obj =
container_of(ref, struct bnxt_re_dbr_obj, usecnt);
struct bnxt_re_dev *rdev = obj->rdev;
/* Drop the driver's reference to the mmap entry (_remove()).
* The DPI slot gets freed from bnxt_re_mmap_free() only
* when there's no VMA mapping reference to it.
*/
rdma_user_mmap_entry_remove(&obj->entry->rdma_entry);
bnxt_qplib_free_uc_dpi(&rdev->qplib_res, &obj->dpi);
kfree(obj);
}