[PATCH 1/3] clone.2: Fix typos

[PATCH 1/3] clone.2: Fix typos

[Christian Brauner]

From: Christian Brauner <christian.brauner@ubuntu.com>

Fix two spelling mistakes in manpage describing the clone{2,3}()
syscalls/syscall wrappers.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 man2/clone.2 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/man2/clone.2 b/man2/clone.2
index f67a60067..57a9eaba7 100644
--- a/man2/clone.2
+++ b/man2/clone.2
@@ -70,12 +70,12 @@ create a new ("child") process, in a manner similar to
 .PP
 By contrast with
 .BR fork (2),
-these system cals provide more precise control over what pieces of execution
+these system calls provide more precise control over what pieces of execution
 context are shared between the calling process and the child process.
 For example, using these system calls, the caller can control whether
 or not the two processes share the virtual address space,
 the table of file descriptors, and the table of signal handlers.
-These system calls also allow the new child process to placed
+These system calls also allow the new child process to be placed
 in separate
 .BR namespaces (7).
 .PP

base-commit: 91243dad42a7a62df73e3b1dfbb810adc1b8b654
-- 
2.24.0

[PATCH 2/3] clone.2: Check for MAP_FAILED not NULL on mmap()

[Christian Brauner]

From: Christian Brauner <christian.brauner@ubuntu.com>

If mmap() fails it will return MAP_FAILED which according to the manpage
is (void *)-1 not NULL.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 man2/clone.2 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man2/clone.2 b/man2/clone.2
index 57a9eaba7..faff2ada6 100644
--- a/man2/clone.2
+++ b/man2/clone.2
@@ -1628,7 +1628,7 @@ main(int argc, char *argv[])
 
     stack = mmap(NULL, STACK_SIZE, PROT_READ | PROT_WRITE,
                  MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, \-1, 0);
-    if (stack == NULL)
+    if (stack == MAP_FAILED)
         errExit("mmap");
 
     stackTop = stack + STACK_SIZE;  /* Assume stack grows downward */
-- 
2.24.0

[PATCH 3/3] clone.2: Use pid_t for clone3() {child,parent}_tid

[Christian Brauner]

From: Christian Brauner <christian.brauner@ubuntu.com>

Advertise to userspace that they should use proper pid_t types for
arguments returning a pid.
The kernel-internal struct kernel_clone_args currently uses int as type
and since POSIX mandates that pid_t is a signed integer type and glibc
and friends use int this is not an issue. After the merge window for
v5.5 closes we can switch struct kernel_clone_args over to using pid_t
as well without any danger in regressing current userspace.
Also note, that the new set tid feature which will be merged for v5.5
uses pid_t types as well.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 man2/clone.2 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/man2/clone.2 b/man2/clone.2
index faff2ada6..bf2d7c731 100644
--- a/man2/clone.2
+++ b/man2/clone.2
@@ -183,9 +183,9 @@ is a structure of the following form:
 struct clone_args {
     u64 flags;        /* Flags bit mask */
     u64 pidfd;        /* Where to store PID file descriptor
-                         (\fIint *\fP) */
+                         (\fIpid_t *\fP) */
     u64 child_tid;    /* Where to store child TID,
-                         in child's memory (\fIint *\fP) */
+                         in child's memory (\fIpid_t *\fP) */
     u64 parent_tid;   /* Where to store child TID,
                          in parent's memory (\fIint *\fP) */
     u64 exit_signal;  /* Signal to deliver to parent on
-- 
2.24.0

Re: [PATCH 1/3] clone.2: Fix typos

[Michael Kerrisk (man-pages)]

On 11/16/19 12:41 PM, Christian Brauner wrote:
> From: Christian Brauner <christian.brauner@ubuntu.com>

Thanks, Christian, 

Patch applied.

Cheers,

Michael


> Fix two spelling mistakes in manpage describing the clone{2,3}()
> syscalls/syscall wrappers.
> 
> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
> ---
>  man2/clone.2 | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/man2/clone.2 b/man2/clone.2
> index f67a60067..57a9eaba7 100644
> --- a/man2/clone.2
> +++ b/man2/clone.2
> @@ -70,12 +70,12 @@ create a new ("child") process, in a manner similar to
>  .PP
>  By contrast with
>  .BR fork (2),
> -these system cals provide more precise control over what pieces of execution
> +these system calls provide more precise control over what pieces of execution
>  context are shared between the calling process and the child process.
>  For example, using these system calls, the caller can control whether
>  or not the two processes share the virtual address space,
>  the table of file descriptors, and the table of signal handlers.
> -These system calls also allow the new child process to placed
> +These system calls also allow the new child process to be placed
>  in separate
>  .BR namespaces (7).
>  .PP
> 
> base-commit: 91243dad42a7a62df73e3b1dfbb810adc1b8b654
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

Re: [PATCH 2/3] clone.2: Check for MAP_FAILED not NULL on mmap()

[Michael Kerrisk (man-pages)]

On 11/16/19 12:41 PM, Christian Brauner wrote:
> From: Christian Brauner <christian.brauner@ubuntu.com>
> 
> If mmap() fails it will return MAP_FAILED which according to the manpage
> is (void *)-1 not NULL.

Sigh! Bad editing on my part.

Thanks, Christian.

Patch applied.

Cheers,

Michael



> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
> ---
>  man2/clone.2 | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/man2/clone.2 b/man2/clone.2
> index 57a9eaba7..faff2ada6 100644
> --- a/man2/clone.2
> +++ b/man2/clone.2
> @@ -1628,7 +1628,7 @@ main(int argc, char *argv[])
>  
>      stack = mmap(NULL, STACK_SIZE, PROT_READ | PROT_WRITE,
>                   MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, \-1, 0);
> -    if (stack == NULL)
> +    if (stack == MAP_FAILED)
>          errExit("mmap");
>  
>      stackTop = stack + STACK_SIZE;  /* Assume stack grows downward */
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

Re: [PATCH 3/3] clone.2: Use pid_t for clone3() {child,parent}_tid

[Michael Kerrisk (man-pages)]

On 11/16/19 12:41 PM, Christian Brauner wrote:
> From: Christian Brauner <christian.brauner@ubuntu.com>
>
> Advertise to userspace that they should use proper pid_t types for
> arguments returning a pid.
> The kernel-internal struct kernel_clone_args currently uses int as type
> and since POSIX mandates that pid_t is a signed integer type and glibc
> and friends use int this is not an issue. After the merge window for
> v5.5 closes we can switch struct kernel_clone_args over to using pid_t
> as well without any danger in regressing current userspace.
> Also note, that the new set tid feature which will be merged for v5.5
> uses pid_t types as well.

Thanks taking a further pass throuh this page, Christian, 

Patch applied.

Cheers,

Michael

 
> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
> ---
>  man2/clone.2 | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/man2/clone.2 b/man2/clone.2
> index faff2ada6..bf2d7c731 100644
> --- a/man2/clone.2
> +++ b/man2/clone.2
> @@ -183,9 +183,9 @@ is a structure of the following form:
>  struct clone_args {
>      u64 flags;        /* Flags bit mask */
>      u64 pidfd;        /* Where to store PID file descriptor
> -                         (\fIint *\fP) */
> +                         (\fIpid_t *\fP) */
>      u64 child_tid;    /* Where to store child TID,
> -                         in child's memory (\fIint *\fP) */
> +                         in child's memory (\fIpid_t *\fP) */
>      u64 parent_tid;   /* Where to store child TID,
>                           in parent's memory (\fIint *\fP) */
>      u64 exit_signal;  /* Signal to deliver to parent on
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/