From: "Jiri Slaby (SUSE)" jirislaby@kernel.org
mainline inclusion from mainline-v6.10-rc1 commit 4edd7e96a1f159f43bd1cb82616f81eaddd54262 category: feature bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAOXYG CVE: CVE-2024-44951
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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kfifo: add kfifo_out_linear{,_ptr}()
These are helpers which are going to be used in the serial layer. We need a wrapper around kfifo which provides us with a tail (sometimes "tail" offset, sometimes a pointer) to the kfifo data. And which returns count of available data -- but not larger than to the end of the buffer (hence _linear in the names). I.e. something like CIRC_CNT_TO_END() in the legacy circ_buf.
This patch adds such two helpers.
Signed-off-by: Jiri Slaby (SUSE) jirislaby@kernel.org Cc: Stefani Seibold stefani@seibold.net Cc: Andrew Morton akpm@linux-foundation.org Link: https://lore.kernel.org/r/20240405060826.2521-4-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zhao Yipeng zhaoyipeng5@huawei.com --- include/linux/kfifo.h | 63 +++++++++++++++++++++++++++++++++++++++++++ lib/kfifo.c | 26 ++++++++++++++++++ 2 files changed, 89 insertions(+)
diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h index 0b35a41440ff..0f2e7effe17c 100644 --- a/include/linux/kfifo.h +++ b/include/linux/kfifo.h @@ -828,6 +828,63 @@ __kfifo_uint_must_check_helper( \ }) \ )
+/** + * kfifo_out_linear - gets a tail of/offset to available data + * @fifo: address of the fifo to be used + * @tail: pointer to an unsigned int to store the value of tail + * @n: max. number of elements to point at + * + * This macro obtains the offset (tail) to the available data in the fifo + * buffer and returns the + * numbers of elements available. It returns the available count till the end + * of data or till the end of the buffer. So that it can be used for linear + * data processing (like memcpy() of (@fifo->data + @tail) with count + * returned). + * + * Note that with only one concurrent reader and one concurrent + * writer, you don't need extra locking to use these macro. + */ +#define kfifo_out_linear(fifo, tail, n) \ +__kfifo_uint_must_check_helper( \ +({ \ + typeof((fifo) + 1) __tmp = (fifo); \ + unsigned int *__tail = (tail); \ + unsigned long __n = (n); \ + const size_t __recsize = sizeof(*__tmp->rectype); \ + struct __kfifo *__kfifo = &__tmp->kfifo; \ + (__recsize) ? \ + __kfifo_out_linear_r(__kfifo, __tail, __n, __recsize) : \ + __kfifo_out_linear(__kfifo, __tail, __n); \ +}) \ +) + +/** + * kfifo_out_linear_ptr - gets a pointer to the available data + * @fifo: address of the fifo to be used + * @ptr: pointer to data to store the pointer to tail + * @n: max. number of elements to point at + * + * Similarly to kfifo_out_linear(), this macro obtains the pointer to the + * available data in the fifo buffer and returns the numbers of elements + * available. It returns the available count till the end of available data or + * till the end of the buffer. So that it can be used for linear data + * processing (like memcpy() of @ptr with count returned). + * + * Note that with only one concurrent reader and one concurrent + * writer, you don't need extra locking to use these macro. + */ +#define kfifo_out_linear_ptr(fifo, ptr, n) \ +__kfifo_uint_must_check_helper( \ +({ \ + typeof((fifo) + 1) ___tmp = (fifo); \ + unsigned int ___tail; \ + unsigned int ___n = kfifo_out_linear(___tmp, &___tail, (n)); \ + *(ptr) = ___tmp->kfifo.data + ___tail * kfifo_esize(___tmp); \ + ___n; \ +}) \ +) + + extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size, size_t esize, gfp_t gfp_mask);
@@ -857,6 +914,9 @@ extern unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo, extern unsigned int __kfifo_out_peek(struct __kfifo *fifo, void *buf, unsigned int len);
+extern unsigned int __kfifo_out_linear(struct __kfifo *fifo, + unsigned int *tail, unsigned int n); + extern unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf, unsigned int len, size_t recsize);
@@ -888,6 +948,9 @@ extern void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize); extern unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf, unsigned int len, size_t recsize);
+extern unsigned int __kfifo_out_linear_r(struct __kfifo *fifo, + unsigned int *tail, unsigned int n, size_t recsize); + extern unsigned int __kfifo_max_r(unsigned int len, size_t recsize);
#endif diff --git a/lib/kfifo.c b/lib/kfifo.c index 12f5a347aa13..abad82f6e135 100644 --- a/lib/kfifo.c +++ b/lib/kfifo.c @@ -163,6 +163,19 @@ unsigned int __kfifo_out_peek(struct __kfifo *fifo, } EXPORT_SYMBOL(__kfifo_out_peek);
+unsigned int __kfifo_out_linear(struct __kfifo *fifo, + unsigned int *tail, unsigned int n) +{ + unsigned int size = fifo->mask + 1; + unsigned int off = fifo->out & fifo->mask; + + if (tail) + *tail = off; + + return min3(n, fifo->in - fifo->out, size - off); +} +EXPORT_SYMBOL(__kfifo_out_linear); + unsigned int __kfifo_out(struct __kfifo *fifo, void *buf, unsigned int len) { @@ -473,6 +486,19 @@ unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf, } EXPORT_SYMBOL(__kfifo_out_peek_r);
+unsigned int __kfifo_out_linear_r(struct __kfifo *fifo, + unsigned int *tail, unsigned int n, size_t recsize) +{ + if (fifo->in == fifo->out) + return 0; + + if (tail) + *tail = fifo->out + recsize; + + return min(n, __kfifo_peek_n(fifo, recsize)); +} +EXPORT_SYMBOL(__kfifo_out_linear_r); + unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf, unsigned int len, size_t recsize) {