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| author | Arnd Bergmann <arnd@arndb.de> | 2019-05-15 01:41:42 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-15 05:52:48 +0300 |
| commit | ad312f95d41c9de19313c51e388c4984451c010f (patch) | |
| tree | 970e3683c194486c4497dbe3ae1118b16aac53d8 | |
| parent | 134fca9063ad4851de767d1768180e5dede9a881 (diff) | |
| download | linux-ad312f95d41c9de19313c51e388c4984451c010f.tar.xz | |
fs/select: avoid clang stack usage warning
The select() implementation is carefully tuned to put a sensible amount
of data on the stack for holding a copy of the user space fd_set, but
not too large to risk overflowing the kernel stack.
When building a 32-bit kernel with clang, we need a little more space
than with gcc, which often triggers a warning:
fs/select.c:619:5: error: stack frame size of 1048 bytes in function 'core_sys_select' [-Werror,-Wframe-larger-than=]
int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
I experimentally found that for 32-bit ARM, reducing the maximum stack
usage by 64 bytes keeps us reliably under the warning limit again.
Link: http://lkml.kernel.org/r/20190307090146.1874906-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/poll.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/poll.h b/include/linux/poll.h index 7e0fdcf905d2..1cdc32b1f1b0 100644 --- a/include/linux/poll.h +++ b/include/linux/poll.h @@ -16,7 +16,11 @@ extern struct ctl_table epoll_table[]; /* for sysctl */ /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating additional memory. */ +#ifdef __clang__ +#define MAX_STACK_ALLOC 768 +#else #define MAX_STACK_ALLOC 832 +#endif #define FRONTEND_STACK_ALLOC 256 #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC |