[PATCH 1/4] char: xilinx_hwicap: replace page allocator calls with k[mz]alloc()
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
Date: 2026-08-30 07:48:13
Also in:
linux-arm-kernel, linux-mm, lkml
Subsystem:
char and misc drivers, the rest · Maintainers:
Arnd Bergmann, Greg Kroah-Hartman, Linus Torvalds
hwicap_read() and hwicap_write() allocate temporary buffers used to pass the FPGA configuration data to and from userspace. These buffers can be allocated with kmalloc() as there's nothing special about them to go directly to the page allocator. kmalloc() provides a better API that does not require ugly casts and kfree() does not need to know the size of the freed object. Performance difference between kmalloc() and __get_free_pages() is not measurable as both allocators take an object/page from a per-CPU list for fast path allocations. For the slow path the performance is anyway determined by the amount of reclaim involved rather than by what allocator is used. Replace use of __get_free_page() and get_zeroed_page() with kmalloc() and kzalloc() and free_page() with kfree(). Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@redhat.com (local) Assisted-by: copilot:claude-opus Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> --- drivers/char/xilinx_hwicap/xilinx_hwicap.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/char/xilinx_hwicap/xilinx_hwicap.c b/drivers/char/xilinx_hwicap/xilinx_hwicap.c
index 9bb5fa642fd8..bbeb9b6060dc 100644
--- a/drivers/char/xilinx_hwicap/xilinx_hwicap.c
+++ b/drivers/char/xilinx_hwicap/xilinx_hwicap.c@@ -382,7 +382,7 @@ hwicap_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) 4 - bytes_to_read); } else { /* Get new data from the ICAP, and return what was requested. */ - kbuf = (u32 *) get_zeroed_page(GFP_KERNEL); + kbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); if (!kbuf) { status = -ENOMEM; goto error;
@@ -412,13 +412,13 @@ hwicap_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) /* If we didn't read correctly, then bail out. */ if (status) { - free_page((unsigned long)kbuf); + kfree(kbuf); goto error; } /* If we fail to return the data to the user, then bail out. */ if (copy_to_user(buf, kbuf, bytes_to_read)) { - free_page((unsigned long)kbuf); + kfree(kbuf); status = -EFAULT; goto error; }
@@ -426,7 +426,7 @@ hwicap_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) kbuf, bytes_remaining); drvdata->read_buffer_in_use = bytes_remaining; - free_page((unsigned long)kbuf); + kfree(kbuf); } status = bytes_to_read; error:
@@ -457,7 +457,7 @@ hwicap_write(struct file *file, const char __user *buf, goto error; } - kbuf = (u32 *) __get_free_page(GFP_KERNEL); + kbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!kbuf) { status = -ENOMEM; goto error;
@@ -479,13 +479,13 @@ hwicap_write(struct file *file, const char __user *buf, (((char *)kbuf) + drvdata->write_buffer_in_use), buf + written, len - (drvdata->write_buffer_in_use))) { - free_page((unsigned long)kbuf); + kfree(kbuf); status = -EFAULT; goto error; } } else { if (copy_from_user(kbuf, buf + written, len)) { - free_page((unsigned long)kbuf); + kfree(kbuf); status = -EFAULT; goto error; }
@@ -495,7 +495,7 @@ hwicap_write(struct file *file, const char __user *buf, kbuf, len >> 2); if (status) { - free_page((unsigned long)kbuf); + kfree(kbuf); status = -EFAULT; goto error; }
@@ -516,7 +516,7 @@ hwicap_write(struct file *file, const char __user *buf, } } - free_page((unsigned long)kbuf); + kfree(kbuf); status = written; error: mutex_unlock(&drvdata->sem);
--
2.53.0