On latest RHEL8, dkms fails to build

[davidtluong]

This is what's happening when trying to install on lastest rhel8:

DKMS make.log for gasket-0.0.git.245.66aa4629 for kernel 4.18.0-425.19.2.el8_7.x86_64 (x86_64)
Fri Apr 14 10:29:56 EDT 2023
make -C "/lib/modules/4.18.0-425.19.2.el8_7.x86_64/build" M="/var/lib/dkms/gasket/0.0.git.245.66aa4629/build" modules
make[1]: warning: jobserver unavailable: using -j1.  Add '+' to parent make rule.
make[1]: Entering directory '/usr/src/kernels/4.18.0-425.19.2.el8_7.x86_64'
  CC [M]  /var/lib/dkms/gasket/0.0.git.245.66aa4629/build/gasket_core.o
  CC [M]  /var/lib/dkms/gasket/0.0.git.245.66aa4629/build/gasket_ioctl.o
  CC [M]  /var/lib/dkms/gasket/0.0.git.245.66aa4629/build/gasket_interrupt.o
  CC [M]  /var/lib/dkms/gasket/0.0.git.245.66aa4629/build/gasket_page_table.o
/var/lib/dkms/gasket/0.0.git.245.66aa4629/build/gasket_page_table.c: In function ‘gasket_perform_mapping’:
/var/lib/dkms/gasket/0.0.git.245.66aa4629/build/gasket_page_table.c:541:48: error: passing argument 1 of ‘sg_page_iter_dma_address’ from incompatible pointer type [-Werror=incompatible-pointer-types]
    ptes[i].dma_addr = sg_page_iter_dma_address(sg_iter);
                                                ^~~~~~~
In file included from ./include/linux/dmapool.h:14,
                 from ./include/linux/pci.h:1567,
                 from /var/lib/dkms/gasket/0.0.git.245.66aa4629/build/gasket_page_table.h:15,
                 from /var/lib/dkms/gasket/0.0.git.245.66aa4629/build/gasket_page_table.c:42:
./include/linux/scatterlist.h:445:51: note: expected ‘struct sg_dma_page_iter *’ but argument is of type ‘struct sg_page_iter *’
 sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
                          ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
cc1: some warnings being treated as errors
make[2]: *** [scripts/Makefile.build:318: /var/lib/dkms/gasket/0.0.git.245.66aa4629/build/gasket_page_table.o] Error 1
make[1]: *** [Makefile:1585: _module_/var/lib/dkms/gasket/0.0.git.245.66aa4629/build] Error 2
make[1]: Leaving directory '/usr/src/kernels/4.18.0-425.19.2.el8_7.x86_64'
make: *** [Makefile:15: all] Error 2

[davidtluong]

My fix for this was:

sudo vi +540 /var/lib/dkms/gasket/0.0.git.245.66aa4629/source/gasket_page_table.c

Changing the 5 to a 4 so it doesn't handle the if and goes to the else. Seems that RHEL has sent the corresponding patch through to update sg_page_iter_dma_address

[abeeson]

I'm still seeing this issue on RHEL 8 (Rocky specifically) on kernel 4.18.0-477.27.1.el8_8.x86_64

I had to apply this fix in the comment above, as well as the DMA_BUF call on line 57 was also causing problems, reverting the line on 56 to:
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,16,0)

From this PR:
09385d4

Resolved it, avoiding that line and letting the modules compile OK.

Hope this helps somebody else, not sure why its failing for us, as far as I can tell that should now be OK for RHEL 8.....

[kyleishie]

I'm still seeing this issue on RHEL 8 (Rocky specifically) on kernel 4.18.0-477.27.1.el8_8.x86_64

I had to apply this fix in the comment above, as well as the DMA_BUF call on line 57 was also causing problems, reverting the line on 56 to: #if LINUX_VERSION_CODE >= KERNEL_VERSION(5,16,0)

From this PR: 09385d4

Resolved it, avoiding that line and letting the modules compile OK.

Hope this helps somebody else, not sure why its failing for us, as far as I can tell that should now be OK for RHEL 8.....

This solved it for me. Thanks @abeeson and @rh-dluong

[cyqsimon]

Damn. Fix one problem, introduce five others.

I was the one who raised the issue that led to this change: google#14. It was supposed to be a more elegant solution than the version-based conditionals, which we were trying our hardest to get rid of.

Also please disregard the incorrect autolinked PR. That one fixes RHEL9 backport issues, not this one.

[cyqsimon]

So I did some brief investigation; two problems here:

Problem 1: Macro MODULE_IMPORT_NS is not available before 5.4

/var/lib/dkms/gasket/0.0.git.256.b6a7c6d8/build/gasket_page_table.c:57:1: warning: data definition has no type or storage class
 MODULE_IMPORT_NS(DMA_BUF);
 ^~~~~~~~~~~~~~~~
/var/lib/dkms/gasket/0.0.git.256.b6a7c6d8/build/gasket_page_table.c:57:1: error: type defaults to ‘int’ in declaration of ‘MODULE_IMPORT_NS’ [-Werror=implicit-int]
/var/lib/dkms/gasket/0.0.git.256.b6a7c6d8/build/gasket_page_table.c:57:1: warning: parameter names (without types) in function declaration

The missing macro causes the compiler to see this as a function declaration with implicit return type.

Proposed fix (this probably belongs in upstream):

diff --git a/src/gasket_page_table.c b/src/gasket_page_table.c
index c9067cb..641735c 100644
--- a/src/gasket_page_table.c
+++ b/src/gasket_page_table.c
@@ -53,7 +53,7 @@
 #include <linux/version.h>
 #include <linux/vmalloc.h>
 
-#if __has_include(<linux/dma-buf.h>)
+#if __has_include(<linux/dma-buf.h>) && defined MODULE_IMPORT_NS
 MODULE_IMPORT_NS(DMA_BUF);
 #endif

Problem 2: RHEL8 backports changes in 5.1, breaking conditional compilation

/var/lib/dkms/gasket/0.0.git.256.b6a7c6d8/build/gasket_page_table.c: In function ‘gasket_perform_mapping’:
/var/lib/dkms/gasket/0.0.git.256.b6a7c6d8/build/gasket_page_table.c:541:48: error: passing argument 1 of ‘sg_page_iter_dma_address’ from incompatible pointer type [-Werror=incompatible-pointer-types]
    ptes[i].dma_addr = sg_page_iter_dma_address(sg_iter);
                                                ^~~~~~~

Proposed fix:

diff --git a/src/gasket_page_table.c b/src/gasket_page_table.c
index c9067cb..396975d 100644
--- a/src/gasket_page_table.c
+++ b/src/gasket_page_table.c
@@ -537,7 +537,9 @@ static int gasket_perform_mapping(struct gasket_page_table *pg_tbl,
 				return -EINVAL;
 
 			/* Page already mapped for DMA. */
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 1, 0)
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 1, 0) && \
+  /* First reported for 8.7; could be earlier */ \
+  (defined RHEL_RELEASE_CODE && RHEL_RELEASE_CODE < RHEL_RELEASE_VERSION(8, 7))
 			ptes[i].dma_addr = sg_page_iter_dma_address(sg_iter);
 #else
 			ptes[i].dma_addr = sg_page_iter_dma_address(

---

With both patches applied it compiles without warnings or errors. Tested with Rocky8.10.