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Commit b087498

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Ulrich Dreppertorvalds
Ulrich Drepper
authored and
torvalds
committed
flag parameters: eventfd
This patch adds the new eventfd2 syscall. It extends the old eventfd syscall by one parameter which is meant to hold a flag value. In this patch the only flag support is EFD_CLOEXEC which causes the close-on-exec flag for the returned file descriptor to be set. A new name EFD_CLOEXEC is introduced which in this implementation must have the same value as O_CLOEXEC. The following test must be adjusted for architectures other than x86 and x86-64 and in case the syscall numbers changed. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #include <fcntl.h> #include <stdio.h> #include <unistd.h> #include <sys/syscall.h> #ifndef __NR_eventfd2 # ifdef __x86_64__ # define __NR_eventfd2 290 # elif defined __i386__ # define __NR_eventfd2 328 # else # error "need __NR_eventfd2" # endif #endif #define EFD_CLOEXEC O_CLOEXEC int main (void) { int fd = syscall (__NR_eventfd2, 1, 0); if (fd == -1) { puts ("eventfd2(0) failed"); return 1; } int coe = fcntl (fd, F_GETFD); if (coe == -1) { puts ("fcntl failed"); return 1; } if (coe & FD_CLOEXEC) { puts ("eventfd2(0) sets close-on-exec flag"); return 1; } close (fd); fd = syscall (__NR_eventfd2, 1, EFD_CLOEXEC); if (fd == -1) { puts ("eventfd2(EFD_CLOEXEC) failed"); return 1; } coe = fcntl (fd, F_GETFD); if (coe == -1) { puts ("fcntl failed"); return 1; } if ((coe & FD_CLOEXEC) == 0) { puts ("eventfd2(EFD_CLOEXEC) does not set close-on-exec flag"); return 1; } close (fd); puts ("OK"); return 0; } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [akpm@linux-foundation.org: add sys_ni stub] Signed-off-by: Ulrich Drepper <drepper@redhat.com> Acked-by: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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lines changed

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lines changed

‎arch/x86/ia32/ia32entry.S

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -827,4 +827,5 @@ ia32_sys_call_table:
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.quad compat_sys_timerfd_settime /* 325 */
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.quad compat_sys_timerfd_gettime
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.quad compat_sys_signalfd4
830+
.quad sys_eventfd2
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ia32_syscall_end:

‎arch/x86/kernel/syscall_table_32.S

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -327,3 +327,4 @@ ENTRY(sys_call_table)
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.long sys_timerfd_settime /* 325 */
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.long sys_timerfd_gettime
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.long sys_signalfd4
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.long sys_eventfd2

‎fs/eventfd.c

Lines changed: 11 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -198,11 +198,14 @@ struct file *eventfd_fget(int fd)
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return file;
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}
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201-
asmlinkage long sys_eventfd(unsigned int count)
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asmlinkage long sys_eventfd2(unsigned int count, int flags)
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{
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int fd;
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struct eventfd_ctx *ctx;
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206+
if (flags & ~EFD_CLOEXEC)
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return -EINVAL;
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ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
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if (!ctx)
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return -ENOMEM;
@@ -214,9 +217,15 @@ asmlinkage long sys_eventfd(unsigned int count)
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* When we call this, the initialization must be complete, since
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* anon_inode_getfd() will install the fd.
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*/
217-
fd = anon_inode_getfd("[eventfd]", &eventfd_fops, ctx, 0);
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fd = anon_inode_getfd("[eventfd]", &eventfd_fops, ctx,
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flags & O_CLOEXEC);
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if (fd < 0)
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kfree(ctx);
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return fd;
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}
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227+
asmlinkage long sys_eventfd(unsigned int count)
228+
{
229+
return sys_eventfd2(count, 0);
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}
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‎include/asm-x86/unistd_32.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -333,6 +333,7 @@
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#define __NR_timerfd_settime 325
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#define __NR_timerfd_gettime 326
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#define __NR_signalfd4 327
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#define __NR_eventfd2 328
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#ifdef __KERNEL__
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‎include/asm-x86/unistd_64.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -643,6 +643,8 @@ __SYSCALL(__NR_timerfd_gettime, sys_timerfd_gettime)
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__SYSCALL(__NR_paccept, sys_paccept)
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#define __NR_signalfd4 289
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__SYSCALL(__NR_signalfd4, sys_signalfd4)
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#define __NR_eventfd2 290
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__SYSCALL(__NR_eventfd2, sys_eventfd2)
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#ifndef __NO_STUBS

‎include/linux/eventfd.h

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -10,6 +10,12 @@
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#ifdef CONFIG_EVENTFD
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/* For O_CLOEXEC */
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#include <linux/fcntl.h>
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/* Flags for eventfd2. */
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#define EFD_CLOEXEC O_CLOEXEC
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struct file *eventfd_fget(int fd);
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int eventfd_signal(struct file *file, int n);
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‎include/linux/syscalls.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -617,6 +617,7 @@ asmlinkage long sys_timerfd_settime(int ufd, int flags,
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struct itimerspec __user *otmr);
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asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr);
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asmlinkage long sys_eventfd(unsigned int count);
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asmlinkage long sys_eventfd2(unsigned int count, int flags);
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asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
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int kernel_execve(const char *filename, char *const argv[], char *const envp[]);

‎kernel/sys_ni.c

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -164,3 +164,4 @@ cond_syscall(sys_timerfd_gettime);
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cond_syscall(compat_sys_timerfd_settime);
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cond_syscall(compat_sys_timerfd_gettime);
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cond_syscall(sys_eventfd);
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cond_syscall(sys_eventfd2);

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