[PATCH liburing 0/7] C++ and Travis patches

[PATCH liburing 0/7] C++ and Travis patches

[Bart Van Assche]

Hi Jens,

This patch series includes patches that restore C++ compatibility, that
restore clang compatibility and also that improve the Travis build. Please
consider these patches for inclusion in the official liburing repository.

Thanks,

Bart.

Bart Van Assche (7):
  src/Makefile: Only specify -shared at link time
  src/include/liburing/barrier.h: Restore clang compatibility
  Make the liburing header files again compatible with C++
  Add a C++ unit test
  configure: Use $CC and $CXX as default compilers if set
  .travis.yml: Change the language from C to C++
  .travis.yml: Run tests as root and ignore test results

 .travis.yml                     |  4 +--
 configure                       |  6 ++--
 src/Makefile                    |  4 +--
 src/include/liburing.h          |  8 +++---
 src/include/liburing/barrier.h  | 49 +++++++++++++++++++++++++++++----
 src/include/liburing/io_uring.h |  8 ++++++
 test/Makefile                   | 12 ++++++++
 test/sq-full-cpp.cc             | 45 ++++++++++++++++++++++++++++++
 8 files changed, 120 insertions(+), 16 deletions(-)
 create mode 100644 test/sq-full-cpp.cc

[PATCH liburing 1/7] src/Makefile: Only specify -shared at link time

[Bart Van Assche]

Since -shared only takes effect when linking, only specify it when linking.
This patch fixes the following clang warning:

clang-10.0: warning: argument unused during compilation: '-shared' [-Wunused-command-line-argument]

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 src/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Makefile b/src/Makefile
index 3099f7cd51ec..44a95ad78afa 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -6,7 +6,7 @@ libdevdir ?= $(prefix)/lib
 CFLAGS ?= -g -fomit-frame-pointer -O2
 override CFLAGS += -Wall -Wextra -Wno-unused-parameter -Wno-sign-compare\
 	-Iinclude/ -include ../config-host.h
-SO_CFLAGS=-shared -fPIC $(CFLAGS)
+SO_CFLAGS=-fPIC $(CFLAGS)
 L_CFLAGS=$(CFLAGS)
 LINK_FLAGS=
 LINK_FLAGS+=$(LDFLAGS)
@@ -51,7 +51,7 @@ liburing.a: $(liburing_objs)
 	$(QUIET_RANLIB)$(RANLIB) liburing.a
 
 $(libname): $(liburing_sobjs) liburing.map
-	$(QUIET_CC)$(CC) $(SO_CFLAGS) -Wl,--version-script=liburing.map -Wl,-soname=$(soname) -o $@ $(liburing_sobjs) $(LINK_FLAGS)
+	$(QUIET_CC)$(CC) $(SO_CFLAGS) -shared -Wl,--version-script=liburing.map -Wl,-soname=$(soname) -o $@ $(liburing_sobjs) $(LINK_FLAGS)
 
 install: $(all_targets)
 	install -D -m 644 include/liburing/io_uring.h $(includedir)/liburing/io_uring.h

[PATCH liburing 2/7] src/include/liburing/barrier.h: Restore clang compatibility

[Bart Van Assche]

This patch fixes the following class of clang compiler errors:

include/liburing.h:150:3: error: address argument to atomic operation must be a
      pointer to _Atomic type ('unsigned int *' invalid)
                io_uring_smp_store_release(cq->khead, *cq->khead + nr);
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: b9c0bf79aa87 ("src/include/liburing/barrier.h: Use C11 atomics")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 src/include/liburing/barrier.h | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/include/liburing/barrier.h b/src/include/liburing/barrier.h
index c8aa4210371c..57324348466b 100644
--- a/src/include/liburing/barrier.h
+++ b/src/include/liburing/barrier.h
@@ -24,13 +24,17 @@ after the acquire operation executes. This is implemented using
 */
 
 #define IO_URING_WRITE_ONCE(var, val)				\
-	atomic_store_explicit(&(var), (val), memory_order_relaxed)
+	atomic_store_explicit((_Atomic typeof(var) *)&(var),	\
+			      (val), memory_order_relaxed)
 #define IO_URING_READ_ONCE(var)					\
-	atomic_load_explicit(&(var), memory_order_relaxed)
+	atomic_load_explicit((_Atomic typeof(var) *)&(var),	\
+			     memory_order_relaxed)
 
 #define io_uring_smp_store_release(p, v)			\
-	atomic_store_explicit((p), (v), memory_order_release)
+	atomic_store_explicit((_Atomic typeof(*(p)) *)(p), (v), \
+			      memory_order_release)
 #define io_uring_smp_load_acquire(p)				\
-	atomic_load_explicit((p), memory_order_acquire)
+	atomic_load_explicit((_Atomic typeof(*(p)) *)(p),	\
+			     memory_order_acquire)
 
 #endif /* defined(LIBURING_BARRIER_H) */

[PATCH liburing 3/7] Make the liburing header files again compatible with C++

[Bart Van Assche]

Include <atomic> instead of <stdatomic.h> if built with a C++ compiler.

Fixes: b9c0bf79aa87 ("src/include/liburing/barrier.h: Use C11 atomics")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 src/include/liburing.h          |  8 +++----
 src/include/liburing/barrier.h  | 37 +++++++++++++++++++++++++++++++--
 src/include/liburing/io_uring.h |  8 +++++++
 3 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/src/include/liburing.h b/src/include/liburing.h
index c9034fc0df1b..76e2b854f957 100644
--- a/src/include/liburing.h
+++ b/src/include/liburing.h
@@ -2,10 +2,6 @@
 #ifndef LIB_URING_H
 #define LIB_URING_H
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 #include <sys/socket.h>
 #include <sys/uio.h>
 #include <sys/stat.h>
@@ -19,6 +15,10 @@ extern "C" {
 #include "liburing/io_uring.h"
 #include "liburing/barrier.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /*
  * Library interface to io_uring
  */
diff --git a/src/include/liburing/barrier.h b/src/include/liburing/barrier.h
index 57324348466b..a4a59fb499d6 100644
--- a/src/include/liburing/barrier.h
+++ b/src/include/liburing/barrier.h
@@ -2,8 +2,6 @@
 #ifndef LIBURING_BARRIER_H
 #define LIBURING_BARRIER_H
 
-#include <stdatomic.h>
-
 /*
 From the kernel documentation file refcount-vs-atomic.rst:
 
@@ -23,6 +21,40 @@ after the acquire operation executes. This is implemented using
 :c:func:`smp_acquire__after_ctrl_dep`.
 */
 
+#ifdef __cplusplus
+#include <atomic>
+
+template <typename T>
+static inline void IO_URING_WRITE_ONCE(T &var, T val)
+{
+	std::atomic_store_explicit(reinterpret_cast<std::atomic<T> *>(&var),
+				   val, std::memory_order_relaxed);
+}
+template <typename T>
+static inline T IO_URING_READ_ONCE(const T &var)
+{
+	return std::atomic_load_explicit(
+		reinterpret_cast<const std::atomic<T> *>(&var),
+		std::memory_order_relaxed);
+}
+
+template <typename T>
+static inline void io_uring_smp_store_release(T *p, T v)
+{
+	std::atomic_store_explicit(reinterpret_cast<std::atomic<T> *>(p), v,
+				   std::memory_order_release);
+}
+
+template <typename T>
+static inline T io_uring_smp_load_acquire(const T *p)
+{
+	return std::atomic_load_explicit(
+		reinterpret_cast<const std::atomic<T> *>(p),
+		std::memory_order_acquire);
+}
+#else
+#include <stdatomic.h>
+
 #define IO_URING_WRITE_ONCE(var, val)				\
 	atomic_store_explicit((_Atomic typeof(var) *)&(var),	\
 			      (val), memory_order_relaxed)
@@ -36,5 +68,6 @@ after the acquire operation executes. This is implemented using
 #define io_uring_smp_load_acquire(p)				\
 	atomic_load_explicit((_Atomic typeof(*(p)) *)(p),	\
 			     memory_order_acquire)
+#endif
 
 #endif /* defined(LIBURING_BARRIER_H) */
diff --git a/src/include/liburing/io_uring.h b/src/include/liburing/io_uring.h
index 785a6a4f2233..6a73522de0cb 100644
--- a/src/include/liburing/io_uring.h
+++ b/src/include/liburing/io_uring.h
@@ -11,6 +11,10 @@
 #include <linux/fs.h>
 #include <linux/types.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /*
  * IO submission data structure (Submission Queue Entry)
  */
@@ -289,4 +293,8 @@ struct io_uring_probe {
 	struct io_uring_probe_op ops[0];
 };
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif

[PATCH liburing 4/7] Add a C++ unit test

[Bart Van Assche]

Since the liburing header files support C++ compilers, add a C++ unit test.
This helps to verify C++ compatibility of the liburing header files.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 test/Makefile       | 12 ++++++++++++
 test/sq-full-cpp.cc | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 test/sq-full-cpp.cc

diff --git a/test/Makefile b/test/Makefile
index e103296fabdd..c80ad421a938 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -8,6 +8,7 @@ XCFLAGS =
 override CFLAGS += -Wall -Wextra -Wno-unused-parameter -Wno-sign-compare\
 	-D_GNU_SOURCE -D__SANE_USERSPACE_TYPES__ -L../src/ \
 	-I../src/include/ -include ../config-host.h
+CXXFLAGS += $(CFLAGS) -std=c++11
 
 all_targets += poll poll-cancel ring-leak fsync io_uring_setup io_uring_register \
 	       io_uring_enter nop sq-full cq-full 35fa71a030ca-test \
@@ -36,11 +37,18 @@ ifdef CONFIG_HAVE_STATX
 all_targets += statx
 endif
 
+ifdef CONFIG_HAVE_CXX
+all_targets += sq-full-cpp
+endif
+
 all: $(all_targets)
 
 %: %.c
 	$(QUIET_CC)$(CC) $(CFLAGS) -o $@ $< -luring $(XCFLAGS)
 
+%: %.cc
+	$(QUIET_CC)$(CXX) $(CXXFLAGS) -o $@ $< -luring $(XCFLAGS)
+
 test_srcs := poll.c poll-cancel.c ring-leak.c fsync.c io_uring_setup.c \
 	io_uring_register.c io_uring_enter.c nop.c sq-full.c cq-full.c \
 	35fa71a030ca-test.c 917257daa0fe-test.c b19062a56726-test.c \
@@ -63,6 +71,10 @@ ifdef CONFIG_HAVE_STATX
 test_srcs += statx.c
 endif
 
+ifdef CONFIG_HAVE_CXX
+test_srcs += sq-full-cpp
+endif
+
 test_objs := $(patsubst %.c,%.ol,$(test_srcs))
 
 35fa71a030ca-test: XCFLAGS = -lpthread
diff --git a/test/sq-full-cpp.cc b/test/sq-full-cpp.cc
new file mode 100644
index 000000000000..ba400996e615
--- /dev/null
+++ b/test/sq-full-cpp.cc
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Description: test SQ queue full condition
+ *
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+
+#include "liburing.h"
+
+int main(int argc, char *argv[])
+{
+	struct io_uring_sqe *sqe;
+	struct io_uring ring;
+	int ret, i;
+
+	if (argc > 1)
+		return 0;
+
+	ret = io_uring_queue_init(8, &ring, 0);
+	if (ret) {
+		fprintf(stderr, "ring setup failed: %d\n", ret);
+		return 1;
+
+	}
+
+	i = 0;
+	while ((sqe = io_uring_get_sqe(&ring)) != NULL)
+		i++;
+
+	if (i != 8) {
+		fprintf(stderr, "Got %d SQEs, wanted 8\n", i);
+		goto err;
+	}
+
+	io_uring_queue_exit(&ring);
+	return 0;
+err:
+	io_uring_queue_exit(&ring);
+	return 1;
+}

[PATCH liburing 5/7] configure: Use $CC and $CXX as default compilers if set

[Bart Van Assche]

This change causes .travis.yml to use the compilers configured in the $CC
and $CXX variables. Additionally, make the configure script show the
compiler names.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 configure | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index c02a97875862..223192b8a5f9 100755
--- a/configure
+++ b/configure
@@ -9,8 +9,8 @@ else
     TMPDIR1="/tmp"
 fi
 
-cc=gcc
-cxx=g++
+cc=${CC:-gcc}
+cxx=${CXX:-g++}
 
 for opt do
   optarg=$(expr "x$opt" : 'x[^=]*=\(.*\)')
@@ -315,7 +315,9 @@ if test "$has_cxx" = "yes"; then
 fi
 
 echo "CC=$cc" >> $config_host_mak
+print_config "CC" "$cc"
 echo "CXX=$cxx" >> $config_host_mak
+print_config "CXX" "$cxx"
 
 # generate compat.h
 compat_h="src/include/liburing/compat.h"

[PATCH liburing 6/7] .travis.yml: Change the language from C to C++

[Bart Van Assche]

This causes Travis to set both the CC and CXX environment variables instead
of only CC.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 .travis.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index 7ed15c7ab142..69da3c07df7d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,4 @@
-language: c
+language: cpp
 os:
   - linux
 compiler:

[PATCH liburing 7/7] .travis.yml: Run tests as root and ignore test results

[Bart Van Assche]

Since many tests require root privileges, run the tests with root privileges.
Ignore the test results because the kernel of Travis VMs is too old for all
tests to pass.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 .travis.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index 69da3c07df7d..e02fdd03392f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,4 +19,4 @@ before_install:
   - EXTRA_CFLAGS="-Werror"
 script:
   - ./configure && make
-  - make runtests
+  - sudo make runtests || true

Re: [PATCH liburing 0/7] C++ and Travis patches

[Jens Axboe]

On 6/28/20 1:58 PM, Bart Van Assche wrote:
> Hi Jens,
> 
> This patch series includes patches that restore C++ compatibility, that
> restore clang compatibility and also that improve the Travis build. Please
> consider these patches for inclusion in the official liburing repository.

Looks good to me, thanks Bart.

-- 
Jens Axboe