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-rw-r--r--lib/iov_iter.c270
1 files changed, 152 insertions, 118 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 639d5e7014c1..fb29c02c6a3c 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -325,28 +325,33 @@ done:
static bool sanity(const struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
- int idx = i->idx;
- int next = pipe->curbuf + pipe->nrbufs;
+ unsigned int p_head = pipe->head;
+ unsigned int p_tail = pipe->tail;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int p_occupancy = pipe_occupancy(p_head, p_tail);
+ unsigned int i_head = i->head;
+ unsigned int idx;
+
if (i->iov_offset) {
struct pipe_buffer *p;
- if (unlikely(!pipe->nrbufs))
+ if (unlikely(p_occupancy == 0))
goto Bad; // pipe must be non-empty
- if (unlikely(idx != ((next - 1) & (pipe->buffers - 1))))
+ if (unlikely(i_head != p_head - 1))
goto Bad; // must be at the last buffer...
- p = &pipe->bufs[idx];
+ p = &pipe->bufs[i_head & p_mask];
if (unlikely(p->offset + p->len != i->iov_offset))
goto Bad; // ... at the end of segment
} else {
- if (idx != (next & (pipe->buffers - 1)))
+ if (i_head != p_head)
goto Bad; // must be right after the last buffer
}
return true;
Bad:
- printk(KERN_ERR "idx = %d, offset = %zd\n", i->idx, i->iov_offset);
- printk(KERN_ERR "curbuf = %d, nrbufs = %d, buffers = %d\n",
- pipe->curbuf, pipe->nrbufs, pipe->buffers);
- for (idx = 0; idx < pipe->buffers; idx++)
+ printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset);
+ printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n",
+ p_head, p_tail, pipe->ring_size);
+ for (idx = 0; idx < pipe->ring_size; idx++)
printk(KERN_ERR "[%p %p %d %d]\n",
pipe->bufs[idx].ops,
pipe->bufs[idx].page,
@@ -359,18 +364,15 @@ Bad:
#define sanity(i) true
#endif
-static inline int next_idx(int idx, struct pipe_inode_info *pipe)
-{
- return (idx + 1) & (pipe->buffers - 1);
-}
-
static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
struct pipe_buffer *buf;
+ unsigned int p_tail = pipe->tail;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int i_head = i->head;
size_t off;
- int idx;
if (unlikely(bytes > i->count))
bytes = i->count;
@@ -382,8 +384,7 @@ static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t by
return 0;
off = i->iov_offset;
- idx = i->idx;
- buf = &pipe->bufs[idx];
+ buf = &pipe->bufs[i_head & p_mask];
if (off) {
if (offset == off && buf->page == page) {
/* merge with the last one */
@@ -391,18 +392,21 @@ static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t by
i->iov_offset += bytes;
goto out;
}
- idx = next_idx(idx, pipe);
- buf = &pipe->bufs[idx];
+ i_head++;
+ buf = &pipe->bufs[i_head & p_mask];
}
- if (idx == pipe->curbuf && pipe->nrbufs)
+ if (pipe_full(i_head, p_tail, pipe->max_usage))
return 0;
- pipe->nrbufs++;
+
buf->ops = &page_cache_pipe_buf_ops;
- get_page(buf->page = page);
+ get_page(page);
+ buf->page = page;
buf->offset = offset;
buf->len = bytes;
+
+ pipe->head = i_head + 1;
i->iov_offset = offset + bytes;
- i->idx = idx;
+ i->head = i_head;
out:
i->count -= bytes;
return bytes;
@@ -480,24 +484,30 @@ static inline bool allocated(struct pipe_buffer *buf)
return buf->ops == &default_pipe_buf_ops;
}
-static inline void data_start(const struct iov_iter *i, int *idxp, size_t *offp)
+static inline void data_start(const struct iov_iter *i,
+ unsigned int *iter_headp, size_t *offp)
{
+ unsigned int p_mask = i->pipe->ring_size - 1;
+ unsigned int iter_head = i->head;
size_t off = i->iov_offset;
- int idx = i->idx;
- if (off && (!allocated(&i->pipe->bufs[idx]) || off == PAGE_SIZE)) {
- idx = next_idx(idx, i->pipe);
+
+ if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) ||
+ off == PAGE_SIZE)) {
+ iter_head++;
off = 0;
}
- *idxp = idx;
+ *iter_headp = iter_head;
*offp = off;
}
static size_t push_pipe(struct iov_iter *i, size_t size,
- int *idxp, size_t *offp)
+ int *iter_headp, size_t *offp)
{
struct pipe_inode_info *pipe = i->pipe;
+ unsigned int p_tail = pipe->tail;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int iter_head;
size_t off;
- int idx;
ssize_t left;
if (unlikely(size > i->count))
@@ -506,33 +516,34 @@ static size_t push_pipe(struct iov_iter *i, size_t size,
return 0;
left = size;
- data_start(i, &idx, &off);
- *idxp = idx;
+ data_start(i, &iter_head, &off);
+ *iter_headp = iter_head;
*offp = off;
if (off) {
left -= PAGE_SIZE - off;
if (left <= 0) {
- pipe->bufs[idx].len += size;
+ pipe->bufs[iter_head & p_mask].len += size;
return size;
}
- pipe->bufs[idx].len = PAGE_SIZE;
- idx = next_idx(idx, pipe);
+ pipe->bufs[iter_head & p_mask].len = PAGE_SIZE;
+ iter_head++;
}
- while (idx != pipe->curbuf || !pipe->nrbufs) {
+ while (!pipe_full(iter_head, p_tail, pipe->max_usage)) {
+ struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask];
struct page *page = alloc_page(GFP_USER);
if (!page)
break;
- pipe->nrbufs++;
- pipe->bufs[idx].ops = &default_pipe_buf_ops;
- pipe->bufs[idx].page = page;
- pipe->bufs[idx].offset = 0;
- if (left <= PAGE_SIZE) {
- pipe->bufs[idx].len = left;
+
+ buf->ops = &default_pipe_buf_ops;
+ buf->page = page;
+ buf->offset = 0;
+ buf->len = min_t(ssize_t, left, PAGE_SIZE);
+ left -= buf->len;
+ iter_head++;
+ pipe->head = iter_head;
+
+ if (left == 0)
return size;
- }
- pipe->bufs[idx].len = PAGE_SIZE;
- left -= PAGE_SIZE;
- idx = next_idx(idx, pipe);
}
return size - left;
}
@@ -541,23 +552,26 @@ static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int i_head;
size_t n, off;
- int idx;
if (!sanity(i))
return 0;
- bytes = n = push_pipe(i, bytes, &idx, &off);
+ bytes = n = push_pipe(i, bytes, &i_head, &off);
if (unlikely(!n))
return 0;
- for ( ; n; idx = next_idx(idx, pipe), off = 0) {
+ do {
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
- memcpy_to_page(pipe->bufs[idx].page, off, addr, chunk);
- i->idx = idx;
+ memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk);
+ i->head = i_head;
i->iov_offset = off + chunk;
n -= chunk;
addr += chunk;
- }
+ off = 0;
+ i_head++;
+ } while (n);
i->count -= bytes;
return bytes;
}
@@ -573,28 +587,31 @@ static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
__wsum *csum, struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int i_head;
size_t n, r;
size_t off = 0;
__wsum sum = *csum;
- int idx;
if (!sanity(i))
return 0;
- bytes = n = push_pipe(i, bytes, &idx, &r);
+ bytes = n = push_pipe(i, bytes, &i_head, &r);
if (unlikely(!n))
return 0;
- for ( ; n; idx = next_idx(idx, pipe), r = 0) {
+ do {
size_t chunk = min_t(size_t, n, PAGE_SIZE - r);
- char *p = kmap_atomic(pipe->bufs[idx].page);
+ char *p = kmap_atomic(pipe->bufs[i_head & p_mask].page);
sum = csum_and_memcpy(p + r, addr, chunk, sum, off);
kunmap_atomic(p);
- i->idx = idx;
+ i->head = i_head;
i->iov_offset = r + chunk;
n -= chunk;
off += chunk;
addr += chunk;
- }
+ r = 0;
+ i_head++;
+ } while (n);
i->count -= bytes;
*csum = sum;
return bytes;
@@ -645,29 +662,32 @@ static size_t copy_pipe_to_iter_mcsafe(const void *addr, size_t bytes,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int i_head;
size_t n, off, xfer = 0;
- int idx;
if (!sanity(i))
return 0;
- bytes = n = push_pipe(i, bytes, &idx, &off);
+ bytes = n = push_pipe(i, bytes, &i_head, &off);
if (unlikely(!n))
return 0;
- for ( ; n; idx = next_idx(idx, pipe), off = 0) {
+ do {
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
unsigned long rem;
- rem = memcpy_mcsafe_to_page(pipe->bufs[idx].page, off, addr,
- chunk);
- i->idx = idx;
+ rem = memcpy_mcsafe_to_page(pipe->bufs[i_head & p_mask].page,
+ off, addr, chunk);
+ i->head = i_head;
i->iov_offset = off + chunk - rem;
xfer += chunk - rem;
if (rem)
break;
n -= chunk;
addr += chunk;
- }
+ off = 0;
+ i_head++;
+ } while (n);
i->count -= xfer;
return xfer;
}
@@ -925,23 +945,26 @@ EXPORT_SYMBOL(copy_page_from_iter);
static size_t pipe_zero(size_t bytes, struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int i_head;
size_t n, off;
- int idx;
if (!sanity(i))
return 0;
- bytes = n = push_pipe(i, bytes, &idx, &off);
+ bytes = n = push_pipe(i, bytes, &i_head, &off);
if (unlikely(!n))
return 0;
- for ( ; n; idx = next_idx(idx, pipe), off = 0) {
+ do {
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
- memzero_page(pipe->bufs[idx].page, off, chunk);
- i->idx = idx;
+ memzero_page(pipe->bufs[i_head & p_mask].page, off, chunk);
+ i->head = i_head;
i->iov_offset = off + chunk;
n -= chunk;
- }
+ off = 0;
+ i_head++;
+ } while (n);
i->count -= bytes;
return bytes;
}
@@ -987,20 +1010,26 @@ EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
static inline void pipe_truncate(struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
- if (pipe->nrbufs) {
+ unsigned int p_tail = pipe->tail;
+ unsigned int p_head = pipe->head;
+ unsigned int p_mask = pipe->ring_size - 1;
+
+ if (!pipe_empty(p_head, p_tail)) {
+ struct pipe_buffer *buf;
+ unsigned int i_head = i->head;
size_t off = i->iov_offset;
- int idx = i->idx;
- int nrbufs = (idx - pipe->curbuf) & (pipe->buffers - 1);
+
if (off) {
- pipe->bufs[idx].len = off - pipe->bufs[idx].offset;
- idx = next_idx(idx, pipe);
- nrbufs++;
+ buf = &pipe->bufs[i_head & p_mask];
+ buf->len = off - buf->offset;
+ i_head++;
}
- while (pipe->nrbufs > nrbufs) {
- pipe_buf_release(pipe, &pipe->bufs[idx]);
- idx = next_idx(idx, pipe);
- pipe->nrbufs--;
+ while (p_head != i_head) {
+ p_head--;
+ pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]);
}
+
+ pipe->head = p_head;
}
}
@@ -1011,18 +1040,20 @@ static void pipe_advance(struct iov_iter *i, size_t size)
size = i->count;
if (size) {
struct pipe_buffer *buf;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int i_head = i->head;
size_t off = i->iov_offset, left = size;
- int idx = i->idx;
+
if (off) /* make it relative to the beginning of buffer */
- left += off - pipe->bufs[idx].offset;
+ left += off - pipe->bufs[i_head & p_mask].offset;
while (1) {
- buf = &pipe->bufs[idx];
+ buf = &pipe->bufs[i_head & p_mask];
if (left <= buf->len)
break;
left -= buf->len;
- idx = next_idx(idx, pipe);
+ i_head++;
}
- i->idx = idx;
+ i->head = i_head;
i->iov_offset = buf->offset + left;
}
i->count -= size;
@@ -1053,25 +1084,27 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll)
i->count += unroll;
if (unlikely(iov_iter_is_pipe(i))) {
struct pipe_inode_info *pipe = i->pipe;
- int idx = i->idx;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int i_head = i->head;
size_t off = i->iov_offset;
while (1) {
- size_t n = off - pipe->bufs[idx].offset;
+ struct pipe_buffer *b = &pipe->bufs[i_head & p_mask];
+ size_t n = off - b->offset;
if (unroll < n) {
off -= unroll;
break;
}
unroll -= n;
- if (!unroll && idx == i->start_idx) {
+ if (!unroll && i_head == i->start_head) {
off = 0;
break;
}
- if (!idx--)
- idx = pipe->buffers - 1;
- off = pipe->bufs[idx].offset + pipe->bufs[idx].len;
+ i_head--;
+ b = &pipe->bufs[i_head & p_mask];
+ off = b->offset + b->len;
}
i->iov_offset = off;
- i->idx = idx;
+ i->head = i_head;
pipe_truncate(i);
return;
}
@@ -1159,13 +1192,13 @@ void iov_iter_pipe(struct iov_iter *i, unsigned int direction,
size_t count)
{
BUG_ON(direction != READ);
- WARN_ON(pipe->nrbufs == pipe->buffers);
+ WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size));
i->type = ITER_PIPE | READ;
i->pipe = pipe;
- i->idx = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
+ i->head = pipe->head;
i->iov_offset = 0;
i->count = count;
- i->start_idx = i->idx;
+ i->start_head = i->head;
}
EXPORT_SYMBOL(iov_iter_pipe);
@@ -1189,11 +1222,12 @@ EXPORT_SYMBOL(iov_iter_discard);
unsigned long iov_iter_alignment(const struct iov_iter *i)
{
+ unsigned int p_mask = i->pipe->ring_size - 1;
unsigned long res = 0;
size_t size = i->count;
if (unlikely(iov_iter_is_pipe(i))) {
- if (size && i->iov_offset && allocated(&i->pipe->bufs[i->idx]))
+ if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask]))
return size | i->iov_offset;
return size;
}
@@ -1231,19 +1265,20 @@ EXPORT_SYMBOL(iov_iter_gap_alignment);
static inline ssize_t __pipe_get_pages(struct iov_iter *i,
size_t maxsize,
struct page **pages,
- int idx,
+ int iter_head,
size_t *start)
{
struct pipe_inode_info *pipe = i->pipe;
- ssize_t n = push_pipe(i, maxsize, &idx, start);
+ unsigned int p_mask = pipe->ring_size - 1;
+ ssize_t n = push_pipe(i, maxsize, &iter_head, start);
if (!n)
return -EFAULT;
maxsize = n;
n += *start;
while (n > 0) {
- get_page(*pages++ = pipe->bufs[idx].page);
- idx = next_idx(idx, pipe);
+ get_page(*pages++ = pipe->bufs[iter_head & p_mask].page);
+ iter_head++;
n -= PAGE_SIZE;
}
@@ -1254,9 +1289,8 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
- unsigned npages;
+ unsigned int iter_head, npages;
size_t capacity;
- int idx;
if (!maxsize)
return 0;
@@ -1264,12 +1298,12 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
if (!sanity(i))
return -EFAULT;
- data_start(i, &idx, start);
- /* some of this one + all after this one */
- npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
- capacity = min(npages,maxpages) * PAGE_SIZE - *start;
+ data_start(i, &iter_head, start);
+ /* Amount of free space: some of this one + all after this one */
+ npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
+ capacity = min(npages, maxpages) * PAGE_SIZE - *start;
- return __pipe_get_pages(i, min(maxsize, capacity), pages, idx, start);
+ return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
}
ssize_t iov_iter_get_pages(struct iov_iter *i,
@@ -1323,9 +1357,8 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
size_t *start)
{
struct page **p;
+ unsigned int iter_head, npages;
ssize_t n;
- int idx;
- int npages;
if (!maxsize)
return 0;
@@ -1333,9 +1366,9 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
if (!sanity(i))
return -EFAULT;
- data_start(i, &idx, start);
- /* some of this one + all after this one */
- npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
+ data_start(i, &iter_head, start);
+ /* Amount of free space: some of this one + all after this one */
+ npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
n = npages * PAGE_SIZE - *start;
if (maxsize > n)
maxsize = n;
@@ -1344,7 +1377,7 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
p = get_pages_array(npages);
if (!p)
return -ENOMEM;
- n = __pipe_get_pages(i, maxsize, p, idx, start);
+ n = __pipe_get_pages(i, maxsize, p, iter_head, start);
if (n > 0)
*pages = p;
else
@@ -1560,15 +1593,15 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
if (unlikely(iov_iter_is_pipe(i))) {
struct pipe_inode_info *pipe = i->pipe;
+ unsigned int iter_head;
size_t off;
- int idx;
if (!sanity(i))
return 0;
- data_start(i, &idx, &off);
+ data_start(i, &iter_head, &off);
/* some of this one + all after this one */
- npages = ((pipe->curbuf - idx - 1) & (pipe->buffers - 1)) + 1;
+ npages = pipe_space_for_user(iter_head, pipe->tail, pipe);
if (npages >= maxpages)
return maxpages;
} else iterate_all_kinds(i, size, v, ({
@@ -1678,6 +1711,7 @@ ssize_t compat_import_iovec(int type,
*iov = p == *iov ? NULL : p;
return n;
}
+EXPORT_SYMBOL(compat_import_iovec);
#endif
int import_single_range(int rw, void __user *buf, size_t len,
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.