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https://github.com/torvalds/linux.git
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23b7776290
Pull scheduler updates from Ingo Molnar:
"The main changes are:
- lockless wakeup support for futexes and IPC message queues
(Davidlohr Bueso, Peter Zijlstra)
- Replace spinlocks with atomics in thread_group_cputimer(), to
improve scalability (Jason Low)
- NUMA balancing improvements (Rik van Riel)
- SCHED_DEADLINE improvements (Wanpeng Li)
- clean up and reorganize preemption helpers (Frederic Weisbecker)
- decouple page fault disabling machinery from the preemption
counter, to improve debuggability and robustness (David
Hildenbrand)
- SCHED_DEADLINE documentation updates (Luca Abeni)
- topology CPU masks cleanups (Bartosz Golaszewski)
- /proc/sched_debug improvements (Srikar Dronamraju)"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (79 commits)
sched/deadline: Remove needless parameter in dl_runtime_exceeded()
sched: Remove superfluous resetting of the p->dl_throttled flag
sched/deadline: Drop duplicate init_sched_dl_class() declaration
sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target
sched/deadline: Make init_sched_dl_class() __init
sched/deadline: Optimize pull_dl_task()
sched/preempt: Add static_key() to preempt_notifiers
sched/preempt: Fix preempt notifiers documentation about hlist_del() within unsafe iteration
sched/stop_machine: Fix deadlock between multiple stop_two_cpus()
sched/debug: Add sum_sleep_runtime to /proc/<pid>/sched
sched/debug: Replace vruntime with wait_sum in /proc/sched_debug
sched/debug: Properly format runnable tasks in /proc/sched_debug
sched/numa: Only consider less busy nodes as numa balancing destinations
Revert 095bebf61a
("sched/numa: Do not move past the balance point if unbalanced")
sched/fair: Prevent throttling in early pick_next_task_fair()
preempt: Reorganize the notrace definitions a bit
preempt: Use preempt_schedule_context() as the official tracing preemption point
sched: Make preempt_schedule_context() function-tracing safe
x86: Remove cpu_sibling_mask() and cpu_core_mask()
x86: Replace cpu_**_mask() with topology_**_cpumask()
...
149 lines
4.1 KiB
C
149 lines
4.1 KiB
C
#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/uaccess.h>
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#include <asm/word-at-a-time.h>
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/* Set bits in the first 'n' bytes when loaded from memory */
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#ifdef __LITTLE_ENDIAN
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# define aligned_byte_mask(n) ((1ul << 8*(n))-1)
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#else
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# define aligned_byte_mask(n) (~0xfful << (BITS_PER_LONG - 8 - 8*(n)))
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#endif
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/*
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* Do a strnlen, return length of string *with* final '\0'.
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* 'count' is the user-supplied count, while 'max' is the
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* address space maximum.
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*
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* Return 0 for exceptions (which includes hitting the address
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* space maximum), or 'count+1' if hitting the user-supplied
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* maximum count.
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*
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* NOTE! We can sometimes overshoot the user-supplied maximum
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* if it fits in a aligned 'long'. The caller needs to check
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* the return value against "> max".
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*/
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static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max)
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{
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const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
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long align, res = 0;
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unsigned long c;
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/*
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* Truncate 'max' to the user-specified limit, so that
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* we only have one limit we need to check in the loop
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*/
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if (max > count)
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max = count;
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/*
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* Do everything aligned. But that means that we
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* need to also expand the maximum..
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*/
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align = (sizeof(long) - 1) & (unsigned long)src;
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src -= align;
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max += align;
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if (unlikely(__get_user(c,(unsigned long __user *)src)))
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return 0;
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c |= aligned_byte_mask(align);
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for (;;) {
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unsigned long data;
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if (has_zero(c, &data, &constants)) {
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data = prep_zero_mask(c, data, &constants);
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data = create_zero_mask(data);
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return res + find_zero(data) + 1 - align;
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}
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res += sizeof(unsigned long);
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/* We already handled 'unsigned long' bytes. Did we do it all ? */
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if (unlikely(max <= sizeof(unsigned long)))
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break;
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max -= sizeof(unsigned long);
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if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
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return 0;
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}
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res -= align;
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/*
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* Uhhuh. We hit 'max'. But was that the user-specified maximum
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* too? If so, return the marker for "too long".
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*/
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if (res >= count)
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return count+1;
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/*
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* Nope: we hit the address space limit, and we still had more
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* characters the caller would have wanted. That's 0.
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*/
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return 0;
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}
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/**
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* strnlen_user: - Get the size of a user string INCLUDING final NUL.
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* @str: The string to measure.
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* @count: Maximum count (including NUL character)
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*
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* Context: User context only. This function may sleep if pagefaults are
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* enabled.
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*
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* Get the size of a NUL-terminated string in user space.
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*
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* Returns the size of the string INCLUDING the terminating NUL.
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* If the string is too long, returns a number larger than @count. User
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* has to check the return value against "> count".
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* On exception (or invalid count), returns 0.
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*
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* NOTE! You should basically never use this function. There is
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* almost never any valid case for using the length of a user space
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* string, since the string can be changed at any time by other
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* threads. Use "strncpy_from_user()" instead to get a stable copy
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* of the string.
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*/
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long strnlen_user(const char __user *str, long count)
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{
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unsigned long max_addr, src_addr;
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if (unlikely(count <= 0))
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return 0;
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max_addr = user_addr_max();
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src_addr = (unsigned long)str;
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if (likely(src_addr < max_addr)) {
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unsigned long max = max_addr - src_addr;
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return do_strnlen_user(str, count, max);
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}
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return 0;
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}
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EXPORT_SYMBOL(strnlen_user);
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/**
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* strlen_user: - Get the size of a user string INCLUDING final NUL.
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* @str: The string to measure.
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*
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* Context: User context only. This function may sleep if pagefaults are
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* enabled.
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*
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* Get the size of a NUL-terminated string in user space.
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*
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* Returns the size of the string INCLUDING the terminating NUL.
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* On exception, returns 0.
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*
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* If there is a limit on the length of a valid string, you may wish to
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* consider using strnlen_user() instead.
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*/
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long strlen_user(const char __user *str)
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{
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unsigned long max_addr, src_addr;
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max_addr = user_addr_max();
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src_addr = (unsigned long)str;
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if (likely(src_addr < max_addr)) {
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unsigned long max = max_addr - src_addr;
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return do_strnlen_user(str, ~0ul, max);
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}
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return 0;
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}
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EXPORT_SYMBOL(strlen_user);
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