git: 46d08fd085dc - stable/13 - LinuxKPI: PCI: add counter for linux_dma_map_phys_common() errors

[Bjoern A. Zeeb]

The branch stable/13 has been updated by bz:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=46d08fd085dcb013b6ae09cd36b272f93fc84574

commit 46d08fd085dcb013b6ae09cd36b272f93fc84574
Author:     Bjoern A. Zeeb <b...@freebsd.org>
AuthorDate: 2022-03-30 17:38:23 +0000
Commit:     Bjoern A. Zeeb <b...@freebsd.org>
CommitDate: 2022-04-14 16:37:53 +0000

    LinuxKPI: PCI: add counter for linux_dma_map_phys_common() errors
    
    LinuxKPI is asking for single-segment mappings.  Some (wireless) drivers
    are using this to map multi-pages and our busdma framework is not very
    friendly to that as single-segments [D31823].  Add a counter so we can
    track when this happens to gather more information.
    
    Sponsored by:   The FreeBSD Foundation
    Reviewed by:    hselasky
    Differential Revision: https://reviews.freebsd.org/D34715
    
    (cherry picked from commit e86707418c8e84e1ebf8b4c5f35ff641c234d067)
---
 sys/compat/linuxkpi/common/src/linux_pci.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/sys/compat/linuxkpi/common/src/linux_pci.c 
b/sys/compat/linuxkpi/common/src/linux_pci.c
index acfc760f092f..3fa6de92bce4 100644
--- a/sys/compat/linuxkpi/common/src/linux_pci.c
+++ b/sys/compat/linuxkpi/common/src/linux_pci.c
@@ -56,6 +56,7 @@ __FBSDID("$FreeBSD$");
 #include <dev/pci/pci_iov.h>
 #include <dev/backlight/backlight.h>
 
+#include <linux/kernel.h>
 #include <linux/kobject.h>
 #include <linux/device.h>
 #include <linux/slab.h>
@@ -77,6 +78,14 @@ __FBSDID("$FreeBSD$");
 /* Undef the linux function macro defined in linux/pci.h */
 #undef pci_get_class
 
+extern int linuxkpi_debug;
+
+SYSCTL_DECL(_compat_linuxkpi);
+
+static counter_u64_t lkpi_pci_nseg1_fail;
+SYSCTL_COUNTER_U64(_compat_linuxkpi, OID_AUTO, lkpi_pci_nseg1_fail, CTLFLAG_RD,
+    &lkpi_pci_nseg1_fail, "Count of busdma mapping failures of 
single-segment");
+
 static device_probe_t linux_pci_probe;
 static device_attach_t linux_pci_attach;
 static device_detach_t linux_pci_detach;
@@ -953,7 +962,7 @@ linux_dma_init(void *arg)
        linux_dma_obj_zone = uma_zcreate("linux_dma_object",
            sizeof(struct linux_dma_obj), NULL, NULL, NULL, NULL,
            UMA_ALIGN_PTR, 0);
-
+       lkpi_pci_nseg1_fail = counter_u64_alloc(M_WAITOK);
 }
 SYSINIT(linux_dma, SI_SUB_DRIVERS, SI_ORDER_THIRD, linux_dma_init, NULL);
 
@@ -961,6 +970,7 @@ static void
 linux_dma_uninit(void *arg)
 {
 
+       counter_u64_free(lkpi_pci_nseg1_fail);
        uma_zdestroy(linux_dma_obj_zone);
        uma_zdestroy(linux_dma_trie_zone);
 }
@@ -1023,6 +1033,9 @@ linux_dma_map_phys_common(struct device *dev, vm_paddr_t 
phys, size_t len,
                bus_dmamap_destroy(obj->dmat, obj->dmamap);
                DMA_PRIV_UNLOCK(priv);
                uma_zfree(linux_dma_obj_zone, obj);
+               counter_u64_add(lkpi_pci_nseg1_fail, 1);
+               if (linuxkpi_debug)
+                       dump_stack();
                return (0);
        }