linux/kernel/relay.c, branch v6.16

relay: remove unused relay_late_setup_files

2025-05-12T00:54:09Z

The last use of relay_late_setup_files() was removed in 2018 by commit 2b47733045aa ("drm/i915/guc: Merge log relay file and channel creation") Remove it and the helper it used. relay_late_setup_files() was used for eventually registering 'buffer only' channels. With it gone, delete the docs that explain how to do that. Which suggests it should be possible to lose the 'has_base_filename' flags. (Are there any other uses??) Link: https://lkml.kernel.org/r/20250418234932.490863-1-linux@treblig.org Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Jens Axboe Cc: Al Viro Cc: Andriy Shevchenko Cc: Jonathan Corbet Signed-off-by: Andrew Morton

relay: use kasprintf() instead of fixed buffer formatting

2025-03-22T05:10:05Z

Improve readability and maintainability by replacing a hard coded string allocation and formatting by using the kasprintf() helper. It also eliminates the GCC compiler warning (with CONFIG_WERROR=y, which is default, it becomes an error: kernel/relay.c:357:42: error: `snprintf' output may be truncated before the last format character [-Werror=format-truncation=] Link: https://lkml.kernel.org/r/20250317212948.1811176-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko Signed-off-by: Andrew Morton

[tree-wide] finally take no_llseek out

2024-09-27T15:18:43Z

no_llseek had been defined to NULL two years ago, in commit 868941b14441 ("fs: remove no_llseek") To quote that commit, At -rc1 we'll need do a mechanical removal of no_llseek - git grep -l -w no_llseek | grep -v porting.rst | while read i; do sed -i '/\/d' $i done would do it. Unfortunately, that hadn't been done. Linus, could you do that now, so that we could finally put that thing to rest? All instances are of the form .llseek = no_llseek, so it's obviously safe. Signed-off-by: Al Viro Signed-off-by: Linus Torvalds

kernel: relay: remove relay_file_splice_read dead code, doesn't work

2023-12-29T20:22:27Z

Documentation/filesystems/relay.rst says to use return debugfs_create_file(filename, mode, parent, buf, &relay_file_operations); and this is the only way relay_file_operations is used. Thus: debugfs_create_file(&relay_file_operations) -> __debugfs_create_file(&debugfs_full_proxy_file_operations, &relay_file_operations) -> dentry{inode: {i_fop: &debugfs_full_proxy_file_operations}, d_fsdata: &relay_file_operations | DEBUGFS_FSDATA_IS_REAL_FOPS_BIT} debugfs_full_proxy_file_operations.open is full_proxy_open, which extracts the &relay_file_operations from the dentry, and allocates via __full_proxy_fops_init() new fops, with trivial wrappers around release, llseek, read, write, poll, and unlocked_ioctl, then replaces the fops on the opened file therewith. Naturally, all thusly-created debugfs files have .splice_read = NULL. This was introduced in commit 49d200deaa68 ("debugfs: prevent access to removed files' private data") from 2016-03-22. AFAICT, relay_file_operations is the only struct file_operations used for debugfs which defines a .splice_read callback. Hooking it up with > diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c > index 5063434be0fc..952fcf5b2afa 100644 > --- a/fs/debugfs/file.c > +++ b/fs/debugfs/file.c > @@ -328,6 +328,11 @@ FULL_PROXY_FUNC(write, ssize_t, filp, > loff_t *ppos), > ARGS(filp, buf, size, ppos)); > > +FULL_PROXY_FUNC(splice_read, long, in, > + PROTO(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe, > + size_t len, unsigned int flags), > + ARGS(in, ppos, pipe, len, flags)); > + > FULL_PROXY_FUNC(unlocked_ioctl, long, filp, > PROTO(struct file *filp, unsigned int cmd, unsigned long arg), > ARGS(filp, cmd, arg)); > @@ -382,6 +387,8 @@ static void __full_proxy_fops_init(struct file_operations *proxy_fops, > proxy_fops->write = full_proxy_write; > if (real_fops->poll) > proxy_fops->poll = full_proxy_poll; > + if (real_fops->splice_read) > + proxy_fops->splice_read = full_proxy_splice_read; > if (real_fops->unlocked_ioctl) > proxy_fops->unlocked_ioctl = full_proxy_unlocked_ioctl; > } shows it just doesn't work, and splicing always instantly returns empty (subsequent reads actually return the contents). No-one noticed it became dead code in 2016, who knows if it worked back then. Clearly no-one cares; just delete it. Link: https://lkml.kernel.org/r/dtexwpw6zcdx7dkx3xj5gyjp5syxmyretdcbcdtvrnukd4vvuh@tarta.nabijaczleweli.xyz Signed-off-by: Ahelenia Ziemiańska Cc: Greg Kroah-Hartman Cc: Li kunyu Cc: Mike Rapoport (IBM) Cc: Rafael J. Wysocki Cc: Suren Baghdasaryan Cc: Zhang Zhengming Cc: Zhao Lei Signed-off-by: Andrew Morton

kernel: relay: remove unnecessary NULL values from relay_open_buf

2023-08-18T17:18:55Z

buf is assigned first, so it does not need to initialize the assignment. Link: https://lkml.kernel.org/r/20230713234459.2908-1-kunyu@nfschina.com Signed-off-by: Li kunyu Reviewed-by: Andrew Morton Signed-off-by: Andrew Morton

relayfs: fix out-of-bounds access in relay_file_read

2023-05-03T00:23:27Z

There is a crash in relay_file_read, as the var from point to the end of last subbuf. The oops looks something like: pc : __arch_copy_to_user+0x180/0x310 lr : relay_file_read+0x20c/0x2c8 Call trace: __arch_copy_to_user+0x180/0x310 full_proxy_read+0x68/0x98 vfs_read+0xb0/0x1d0 ksys_read+0x6c/0xf0 __arm64_sys_read+0x20/0x28 el0_svc_common.constprop.3+0x84/0x108 do_el0_svc+0x74/0x90 el0_svc+0x1c/0x28 el0_sync_handler+0x88/0xb0 el0_sync+0x148/0x180 We get the condition by analyzing the vmcore: 1). The last produced byte and last consumed byte both at the end of the last subbuf 2). A softirq calls function(e.g __blk_add_trace) to write relay buffer occurs when an program is calling relay_file_read_avail(). relay_file_read relay_file_read_avail relay_file_read_consume(buf, 0, 0); //interrupted by softirq who will write subbuf .... return 1; //read_start point to the end of the last subbuf read_start = relay_file_read_start_pos //avail is equal to subsize avail = relay_file_read_subbuf_avail //from points to an invalid memory address from = buf->start + read_start //system is crashed copy_to_user(buffer, from, avail) Link: https://lkml.kernel.org/r/20230419040203.37676-1-zhang.zhengming@h3c.com Fixes: 8d62fdebdaf9 ("relay file read: start-pos fix") Signed-off-by: Zhang Zhengming Reviewed-by: Zhao Lei Reviewed-by: Zhou Kete Reviewed-by: Pengcheng Yang Cc: Jens Axboe Cc: Signed-off-by: Andrew Morton

mm: replace vma->vm_flags direct modifications with modifier calls

2023-02-10T00:51:39Z

Replace direct modifications to vma->vm_flags with calls to modifier functions to be able to track flag changes and to keep vma locking correctness. [akpm@linux-foundation.org: fix drivers/misc/open-dice.c, per Hyeonggon Yoo] Link: https://lkml.kernel.org/r/20230126193752.297968-5-surenb@google.com Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko Acked-by: Mel Gorman Acked-by: Mike Rapoport (IBM) Acked-by: Sebastian Reichel Reviewed-by: Liam R. Howlett Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Andy Lutomirski Cc: Arjun Roy Cc: Axel Rasmussen Cc: David Hildenbrand Cc: David Howells Cc: Davidlohr Bueso Cc: David Rientjes Cc: Eric Dumazet Cc: Greg Thelen Cc: Hugh Dickins Cc: Ingo Molnar Cc: Jann Horn Cc: Joel Fernandes Cc: Johannes Weiner Cc: Kent Overstreet Cc: Laurent Dufour Cc: Lorenzo Stoakes Cc: Matthew Wilcox Cc: Minchan Kim Cc: Paul E. McKenney Cc: Peter Oskolkov Cc: Peter Xu Cc: Peter Zijlstra Cc: Punit Agrawal Cc: Sebastian Andrzej Siewior Cc: Shakeel Butt Cc: Soheil Hassas Yeganeh Cc: Song Liu Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

relay: fix type mismatch when allocating memory in relay_create_buf()

2022-12-12T03:30:19Z

The 'padding' field of the 'rchan_buf' structure is an array of 'size_t' elements, but the memory is allocated for an array of 'size_t *' elements. Found by Linux Verification Center (linuxtesting.org) with SVACE. Link: https://lkml.kernel.org/r/20221129092002.3538384-1-Ilia.Gavrilov@infotecs.ru Fixes: b86ff981a825 ("[PATCH] relay: migrate from relayfs to a generic relay API") Signed-off-by: Ilia.Gavrilov Cc: Colin Ian King Cc: Jens Axboe Cc: wuchi Signed-off-by: Andrew Morton

relay: use strscpy() is more robust and safer

2022-12-12T03:30:18Z

The implementation of strscpy() is more robust and safer. That's now the recommended way to copy NUL terminated strings. Link: https://lkml.kernel.org/r/202211220853259244666@zte.com.cn Signed-off-by: Xu Panda Signed-off-by: Yang Yang Cc: Colin Ian King Cc: Jens Axboe Cc: wuchi Signed-off-by: Andrew Morton

relay: use kvcalloc to alloc page array in relay_alloc_page_array

2022-10-03T21:21:43Z

kvcalloc() is safer because it will check the integer overflows, and using it will simple the logic of allocation size. Link: https://lkml.kernel.org/r/20220909101025.82955-1-wuchi.zero@gmail.com Signed-off-by: wuchi Cc: Christoph Hellwig Cc: Jens Axboe Signed-off-by: Andrew Morton