[PATCH 2/2] libcamera: dma_buf_allocator: Retry ::ioctl on EINTR

[Umang Jain]

V4L userspace API documentation clearly mentions the handling of
EINTR on ioctl(). Align with the xioctl() reference provided in [1].

Retry the ::ioctl() if failed with errno == EINTR. Use a do..while{}
to check the return value of ::ioctl() and errno value. If the return
value is found to be -1, and errno is set with EINTR, the ioctl() call
should be retried.

[1]: https://docs.kernel.org/userspace-api/media/v4l/capture.c.html

Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
---
 src/libcamera/dma_buf_allocator.cpp | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/libcamera/dma_buf_allocator.cpp b/src/libcamera/dma_buf_allocator.cpp
index be6efb89..5b469b19 100644
--- a/src/libcamera/dma_buf_allocator.cpp
+++ b/src/libcamera/dma_buf_allocator.cpp
@@ -128,6 +128,8 @@ DmaBufAllocator::~DmaBufAllocator() = default;
  */
 UniqueFD DmaBufAllocator::allocFromUDmaBuf(const char *name, std::size_t size)
 {
+	int ret;
+
 	/* Size must be a multiple of the page size. Round it up. */
 	std::size_t pageMask = sysconf(_SC_PAGESIZE) - 1;
 	size = (size + pageMask) & ~pageMask;
@@ -144,7 +146,10 @@ UniqueFD DmaBufAllocator::allocFromUDmaBuf(const char *name, std::size_t size)
 	create.offset = 0;
 	create.size = size;
 
-	int ret = ::ioctl(providerHandle_.get(), UDMABUF_CREATE, &create);
+	do {
+		ret = ::ioctl(providerHandle_.get(), UDMABUF_CREATE, &create);
+	} while (ret == -1 && errno == EINTR);
+
 	if (ret < 0) {
 		ret = errno;
 		LOG(DmaBufAllocator, Error)
@@ -165,7 +170,10 @@ UniqueFD DmaBufAllocator::allocFromHeap(const char *name, std::size_t size)
 	alloc.len = size;
 	alloc.fd_flags = O_CLOEXEC | O_RDWR;
 
-	ret = ::ioctl(providerHandle_.get(), DMA_HEAP_IOCTL_ALLOC, &alloc);
+	do {
+		ret = ::ioctl(providerHandle_.get(), DMA_HEAP_IOCTL_ALLOC, &alloc);
+	} while (ret == -1 && errno == EINTR);
+
 	if (ret < 0) {
 		LOG(DmaBufAllocator, Error)
 			<< "dma-heap allocation failure for " << name;
@@ -173,7 +181,11 @@ UniqueFD DmaBufAllocator::allocFromHeap(const char *name, std::size_t size)
 	}
 
 	UniqueFD allocFd(alloc.fd);
-	ret = ::ioctl(allocFd.get(), DMA_BUF_SET_NAME, name);
+
+	do {
+		ret = ::ioctl(allocFd.get(), DMA_BUF_SET_NAME, name);
+	} while (ret == -1 && errno == EINTR);
+
 	if (ret < 0) {
 		LOG(DmaBufAllocator, Error)
 			<< "dma-heap naming failure for " << name;
-- 
2.45.2