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[PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

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  [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-21 21:50 +0200
    Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from  kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-22 12:20 +0200
      Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-23 01:40 +0200
        Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from  kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-23 04:40 +0200
          Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole  from kexec_add_buffer. Dave Young <dyoung@redhat.com> - 2016-06-23 07:50 +0200
            Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer. Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> - 2016-06-23 17:40 +0200

#1428113 — [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
implementation to find free memory for the purgatory stack.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/kexec.h |  4 ++++
 kernel/kexec_file.c   | 66 ++++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 3d91bcfc180d..4ca6f5f95d66 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -227,6 +227,10 @@ extern asmlinkage long sys_kexec_load(unsigned long entry,
 					struct kexec_segment __user *segments,
 					unsigned long flags);
 extern int kernel_kexec(void);
+int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
+			  unsigned long align, unsigned long min_addr,
+			  unsigned long max_addr, bool top_down,
+			  unsigned long *addr);
 extern int kexec_add_buffer(struct kimage *image, char *buffer,
 			    unsigned long bufsz, unsigned long memsz,
 			    unsigned long buf_align, unsigned long buf_min,
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b1f1f6402518..85a515511925 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -449,6 +449,46 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
 }
 
+/**
+ * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
+ * @image:	kexec image being updated.
+ * @size:	Memory size.
+ * @align:	Minimum alignment needed.
+ * @min_addr:	Minimum starting address.
+ * @max_addr:	Maximum end address.
+ * @top_down	Find the highest free memory region?
+ * @addr	On success, will have start address of the memory region found.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
+			  unsigned long align, unsigned long min_addr,
+			  unsigned long max_addr, bool top_down,
+			  unsigned long *addr)
+{
+	int ret;
+	struct kexec_buf buf;
+
+	memset(&buf, 0, sizeof(struct kexec_buf));
+	buf.image = image;
+
+	buf.memsz = size;
+	buf.buf_align = align;
+	buf.buf_min = min_addr;
+	buf.buf_max = max_addr;
+	buf.top_down = top_down;
+
+	ret = arch_kexec_walk_mem(&buf, locate_mem_hole_callback);
+	if (ret != 1) {
+		/* A suitable memory range could not be found for buffer */
+		return -EADDRNOTAVAIL;
+	}
+
+	*addr = buf.mem;
+
+	return 0;
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -460,8 +500,8 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 {
 
 	struct kexec_segment *ksegment;
-	struct kexec_buf buf, *kbuf;
 	int ret;
+	unsigned long addr, align, size;
 
 	/* Currently adding segment this way is allowed only in file mode */
 	if (!image->file_mode)
@@ -482,29 +522,21 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 		return -EINVAL;
 	}
 
-	memset(&buf, 0, sizeof(struct kexec_buf));
-	kbuf = &buf;
-	kbuf->image = image;
-
-	kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
-	kbuf->buf_align = max(buf_align, PAGE_SIZE);
-	kbuf->buf_min = buf_min;
-	kbuf->buf_max = buf_max;
-	kbuf->top_down = top_down;
+	size = ALIGN(memsz, PAGE_SIZE);
+	align = max(buf_align, PAGE_SIZE);
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
-	if (ret != 1) {
-		/* A suitable memory range could not be found for buffer */
-		return -EADDRNOTAVAIL;
-	}
+	ret = kexec_locate_mem_hole(image, size, align, buf_min, buf_max,
+				    top_down, &addr);
+	if (ret)
+		return ret;
 
 	/* Found a suitable memory range */
 	ksegment = &image->segment[image->nr_segments];
 	ksegment->kbuf = buffer;
 	ksegment->bufsz = bufsz;
-	ksegment->mem = kbuf->mem;
-	ksegment->memsz = kbuf->memsz;
+	ksegment->mem = addr;
+	ksegment->memsz = size;
 	image->nr_segments++;
 	*load_addr = ksegment->mem;
 	return 0;
-- 
1.9.1

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#1428648 — Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
> implementation to find free memory for the purgatory stack.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h |  4 ++++
>  kernel/kexec_file.c   | 66 ++++++++++++++++++++++++++++++++++++++-------------
>  2 files changed, 53 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 3d91bcfc180d..4ca6f5f95d66 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -227,6 +227,10 @@ extern asmlinkage long sys_kexec_load(unsigned long entry,
>  					struct kexec_segment __user *segments,
>  					unsigned long flags);
>  extern int kernel_kexec(void);
> +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> +			  unsigned long align, unsigned long min_addr,
> +			  unsigned long max_addr, bool top_down,
> +			  unsigned long *addr);
>  extern int kexec_add_buffer(struct kimage *image, char *buffer,
>  			    unsigned long bufsz, unsigned long memsz,
>  			    unsigned long buf_align, unsigned long buf_min,
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b1f1f6402518..85a515511925 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -449,6 +449,46 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
>  		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
>  }
>  
> +/**
> + * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
> + * @image:	kexec image being updated.
> + * @size:	Memory size.
> + * @align:	Minimum alignment needed.
> + * @min_addr:	Minimum starting address.
> + * @max_addr:	Maximum end address.
> + * @top_down	Find the highest free memory region?
> + * @addr	On success, will have start address of the memory region found.
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> +			  unsigned long align, unsigned long min_addr,
> +			  unsigned long max_addr, bool top_down,
> +			  unsigned long *addr)
> +{
> +	int ret;
> +	struct kexec_buf buf;
> +
> +	memset(&buf, 0, sizeof(struct kexec_buf));
> +	buf.image = image;
> +
> +	buf.memsz = size;
> +	buf.buf_align = align;
> +	buf.buf_min = min_addr;
> +	buf.buf_max = max_addr;
> +	buf.top_down = top_down;

Since patch 2/9 moved kexec_buf from internal header file to kexec.h it
will be natural to passing a kexec_buf pointer intead of passing all
these arguments in kexec_locate_mem_hole.

kbuf.mem can be used for addr.

> +
> +	ret = arch_kexec_walk_mem(&buf, locate_mem_hole_callback);
> +	if (ret != 1) {
> +		/* A suitable memory range could not be found for buffer */
> +		return -EADDRNOTAVAIL;
> +	}
> +
> +	*addr = buf.mem;
> +
> +	return 0;
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -460,8 +500,8 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  {
>  
>  	struct kexec_segment *ksegment;
> -	struct kexec_buf buf, *kbuf;
>  	int ret;
> +	unsigned long addr, align, size;
>  
>  	/* Currently adding segment this way is allowed only in file mode */
>  	if (!image->file_mode)
> @@ -482,29 +522,21 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  		return -EINVAL;
>  	}
>  
> -	memset(&buf, 0, sizeof(struct kexec_buf));
> -	kbuf = &buf;
> -	kbuf->image = image;
> -
> -	kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
> -	kbuf->buf_align = max(buf_align, PAGE_SIZE);
> -	kbuf->buf_min = buf_min;
> -	kbuf->buf_max = buf_max;
> -	kbuf->top_down = top_down;
> +	size = ALIGN(memsz, PAGE_SIZE);
> +	align = max(buf_align, PAGE_SIZE);
>  
>  	/* Walk the RAM ranges and allocate a suitable range for the buffer */
> -	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
> -	if (ret != 1) {
> -		/* A suitable memory range could not be found for buffer */
> -		return -EADDRNOTAVAIL;
> -	}
> +	ret = kexec_locate_mem_hole(image, size, align, buf_min, buf_max,
> +				    top_down, &addr);
> +	if (ret)
> +		return ret;
>  
>  	/* Found a suitable memory range */
>  	ksegment = &image->segment[image->nr_segments];
>  	ksegment->kbuf = buffer;
>  	ksegment->bufsz = bufsz;
> -	ksegment->mem = kbuf->mem;
> -	ksegment->memsz = kbuf->memsz;
> +	ksegment->mem = addr;
> +	ksegment->memsz = size;
>  	image->nr_segments++;
>  	*load_addr = ksegment->mem;
>  	return 0;

Thanks
Dave

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#1429341

Am Mittwoch, 22 Juni 2016, 18:18:01 schrieb Dave Young:
> On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> > +/**
> > + * kexec_locate_mem_hole - find free memory to load segment or use in
> > purgatory + * @image:	kexec image being updated.
> > + * @size:	Memory size.
> > + * @align:	Minimum alignment needed.
> > + * @min_addr:	Minimum starting address.
> > + * @max_addr:	Maximum end address.
> > + * @top_down	Find the highest free memory region?
> > + * @addr	On success, will have start address of the memory region
> > found.
> > + *
> > + * Return: 0 on success, negative errno on error.
> > + */
> > +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> > +			  unsigned long align, unsigned long min_addr,
> > +			  unsigned long max_addr, bool top_down,
> > +			  unsigned long *addr)
> > +{
> > +	int ret;
> > +	struct kexec_buf buf;
> > +
> > +	memset(&buf, 0, sizeof(struct kexec_buf));
> > +	buf.image = image;
> > +
> > +	buf.memsz = size;
> > +	buf.buf_align = align;
> > +	buf.buf_min = min_addr;
> > +	buf.buf_max = max_addr;
> > +	buf.top_down = top_down;
> 
> Since patch 2/9 moved kexec_buf from internal header file to kexec.h it
> will be natural to passing a kexec_buf pointer intead of passing all
> these arguments in kexec_locate_mem_hole.
> 
> kbuf.mem can be used for addr.

Ok. What about this version?
-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center


Subject: [PATCH 3/9] kexec_file: Factor out kexec_locate_mem_hole from
 kexec_add_buffer.

kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
implementation to find free memory for the purgatory stack.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/kexec.h | 12 +++++++++---
 kernel/kexec_file.c   | 25 ++++++++++++++++++++-----
 2 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 3d91bcfc180d..e8b099da47f5 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -147,9 +147,14 @@ struct kexec_file_ops {
 #endif
 };
 
-/*
- * Keeps track of buffer parameters as provided by caller for requesting
- * memory placement of buffer.
+/**
+ * struct kexec_buf - parameters for finding a place for a buffer in memory
+ * @image:	kexec image in which memory to search.
+ * @size:	Memory size for the buffer.
+ * @align:	Minimum alignment needed.
+ * @min_addr:	Minimum starting address.
+ * @max_addr:	Maximum end address.
+ * @top_down:	Find the highest free memory region?
  */
 struct kexec_buf {
 	struct kimage *image;
@@ -163,6 +168,7 @@ struct kexec_buf {
 
 int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 			       int (*func)(u64, u64, void *));
+int kexec_locate_mem_hole(struct kexec_buf *kbuf);
 #endif /* CONFIG_KEXEC_FILE */
 
 struct kimage {
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b1f1f6402518..445d66add8ca 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -449,6 +449,23 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
 }
 
+/**
+ * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
+ * @kbuf:	Parameters for the memory search.
+ *
+ * On success, kbuf->mem will have the start address of the memory region found.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int kexec_locate_mem_hole(struct kexec_buf *kbuf)
+{
+	int ret;
+
+	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
+
+	return ret == 1 ? 0 : -EADDRNOTAVAIL;
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -493,11 +510,9 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 	kbuf->top_down = top_down;
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
-	if (ret != 1) {
-		/* A suitable memory range could not be found for buffer */
-		return -EADDRNOTAVAIL;
-	}
+	ret = kexec_locate_mem_hole(kbuf);
+	if (ret)
+		return ret;
 
 	/* Found a suitable memory range */
 	ksegment = &image->segment[image->nr_segments];
-- 
1.9.1

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#1429413 — Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

On 06/22/16 at 08:34pm, Thiago Jung Bauermann wrote:
> Am Mittwoch, 22 Juni 2016, 18:18:01 schrieb Dave Young:
> > On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> > > +/**
> > > + * kexec_locate_mem_hole - find free memory to load segment or use in
> > > purgatory + * @image:	kexec image being updated.
> > > + * @size:	Memory size.
> > > + * @align:	Minimum alignment needed.
> > > + * @min_addr:	Minimum starting address.
> > > + * @max_addr:	Maximum end address.
> > > + * @top_down	Find the highest free memory region?
> > > + * @addr	On success, will have start address of the memory region
> > > found.
> > > + *
> > > + * Return: 0 on success, negative errno on error.
> > > + */
> > > +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> > > +			  unsigned long align, unsigned long min_addr,
> > > +			  unsigned long max_addr, bool top_down,
> > > +			  unsigned long *addr)
> > > +{
> > > +	int ret;
> > > +	struct kexec_buf buf;
> > > +
> > > +	memset(&buf, 0, sizeof(struct kexec_buf));
> > > +	buf.image = image;
> > > +
> > > +	buf.memsz = size;
> > > +	buf.buf_align = align;
> > > +	buf.buf_min = min_addr;
> > > +	buf.buf_max = max_addr;
> > > +	buf.top_down = top_down;
> > 
> > Since patch 2/9 moved kexec_buf from internal header file to kexec.h it
> > will be natural to passing a kexec_buf pointer intead of passing all
> > these arguments in kexec_locate_mem_hole.
> > 
> > kbuf.mem can be used for addr.
> 
> Ok. What about this version?
> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 
> 
> Subject: [PATCH 3/9] kexec_file: Factor out kexec_locate_mem_hole from
>  kexec_add_buffer.
> 
> kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
> implementation to find free memory for the purgatory stack.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h | 12 +++++++++---
>  kernel/kexec_file.c   | 25 ++++++++++++++++++++-----
>  2 files changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 3d91bcfc180d..e8b099da47f5 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -147,9 +147,14 @@ struct kexec_file_ops {
>  #endif
>  };
>  
> -/*
> - * Keeps track of buffer parameters as provided by caller for requesting
> - * memory placement of buffer.
> +/**
> + * struct kexec_buf - parameters for finding a place for a buffer in memory
> + * @image:	kexec image in which memory to search.
> + * @size:	Memory size for the buffer.
> + * @align:	Minimum alignment needed.
> + * @min_addr:	Minimum starting address.
> + * @max_addr:	Maximum end address.
> + * @top_down:	Find the highest free memory region?

Above parameter comments should go to previous patch.
Other than that it looks good.

Thanks
Dave
>   */
>  struct kexec_buf {
>  	struct kimage *image;
> @@ -163,6 +168,7 @@ struct kexec_buf {
>  
>  int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
>  			       int (*func)(u64, u64, void *));
> +int kexec_locate_mem_hole(struct kexec_buf *kbuf);
>  #endif /* CONFIG_KEXEC_FILE */
>  
>  struct kimage {
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b1f1f6402518..445d66add8ca 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -449,6 +449,23 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
>  		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
>  }
>  
> +/**
> + * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
> + * @kbuf:	Parameters for the memory search.
> + *
> + * On success, kbuf->mem will have the start address of the memory region found.
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int kexec_locate_mem_hole(struct kexec_buf *kbuf)
> +{
> +	int ret;
> +
> +	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
> +
> +	return ret == 1 ? 0 : -EADDRNOTAVAIL;
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -493,11 +510,9 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  	kbuf->top_down = top_down;
>  
>  	/* Walk the RAM ranges and allocate a suitable range for the buffer */
> -	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
> -	if (ret != 1) {
> -		/* A suitable memory range could not be found for buffer */
> -		return -EADDRNOTAVAIL;
> -	}
> +	ret = kexec_locate_mem_hole(kbuf);
> +	if (ret)
> +		return ret;
>  
>  	/* Found a suitable memory range */
>  	ksegment = &image->segment[image->nr_segments];
> -- 
> 1.9.1
> 
> 
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#1429477 — Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

----- Original Message -----
From: "Dave Young" <dyoung@redhat.com>
To: "Thiago Jung Bauermann" <bauerman@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, "Eric Biederman" <ebiederm@xmission.com>
Sent: Thursday, June 23, 2016 10:30:52 AM
Subject: Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

On 06/22/16 at 08:34pm, Thiago Jung Bauermann wrote:
> Am Mittwoch, 22 Juni 2016, 18:18:01 schrieb Dave Young:
> > On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> > > +/**
> > > + * kexec_locate_mem_hole - find free memory to load segment or use in
> > > purgatory + * @image:	kexec image being updated.
> > > + * @size:	Memory size.
> > > + * @align:	Minimum alignment needed.
> > > + * @min_addr:	Minimum starting address.
> > > + * @max_addr:	Maximum end address.
> > > + * @top_down	Find the highest free memory region?
> > > + * @addr	On success, will have start address of the memory region
> > > found.
> > > + *
> > > + * Return: 0 on success, negative errno on error.
> > > + */
> > > +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> > > +			  unsigned long align, unsigned long min_addr,
> > > +			  unsigned long max_addr, bool top_down,
> > > +			  unsigned long *addr)
> > > +{
> > > +	int ret;
> > > +	struct kexec_buf buf;
> > > +
> > > +	memset(&buf, 0, sizeof(struct kexec_buf));
> > > +	buf.image = image;
> > > +
> > > +	buf.memsz = size;
> > > +	buf.buf_align = align;
> > > +	buf.buf_min = min_addr;
> > > +	buf.buf_max = max_addr;
> > > +	buf.top_down = top_down;
> > 
> > Since patch 2/9 moved kexec_buf from internal header file to kexec.h it
> > will be natural to passing a kexec_buf pointer intead of passing all
> > these arguments in kexec_locate_mem_hole.
> > 
> > kbuf.mem can be used for addr.
> 
> Ok. What about this version?
> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 
> 
> Subject: [PATCH 3/9] kexec_file: Factor out kexec_locate_mem_hole from
>  kexec_add_buffer.
> 
> kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
> implementation to find free memory for the purgatory stack.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h | 12 +++++++++---
>  kernel/kexec_file.c   | 25 ++++++++++++++++++++-----
>  2 files changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 3d91bcfc180d..e8b099da47f5 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -147,9 +147,14 @@ struct kexec_file_ops {
>  #endif
>  };
>  
> -/*
> - * Keeps track of buffer parameters as provided by caller for requesting
> - * memory placement of buffer.
> +/**
> + * struct kexec_buf - parameters for finding a place for a buffer in memory
> + * @image:	kexec image in which memory to search.
> + * @size:	Memory size for the buffer.
> + * @align:	Minimum alignment needed.
> + * @min_addr:	Minimum starting address.
> + * @max_addr:	Maximum end address.
> + * @top_down:	Find the highest free memory region?

Hmm, hold on. For declaring a struct in a header file, comment should be
just after each fields, like below, your format is for a function instead:
struct pci_slot {
        struct pci_bus *bus;            /* The bus this slot is on */
        struct list_head list;          /* node in list of slots on this bus */
        struct hotplug_slot *hotplug;   /* Hotplug info (migrate over time) */
        unsigned char number;           /* PCI_SLOT(pci_dev->devfn) */
        struct kobject kobj;
};

BTW, what is @size? there's no size field in kexec_buf. I think it is not
necessary to add these comment, they are easy to understand. If you really
want, please rewrite them correctly, for example "image" description is wrong.
It is not only for searching memory only, top_down description is also bad.

Thanks
Dave

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#1429932

Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young:
> Hmm, hold on. For declaring a struct in a header file, comment should be
> just after each fields, like below, your format is for a function instead:
> struct pci_slot {
>         struct pci_bus *bus;            /* The bus this slot is on */
>         struct list_head list;          /* node in list of slots on this
> bus */ struct hotplug_slot *hotplug;   /* Hotplug info (migrate over
> time) */ unsigned char number;           /* PCI_SLOT(pci_dev->devfn) */
> struct kobject kobj;
> };

The comment style you mention above is not extractable documentation. The 
style I used is what is described in section "kernel-doc for structs, 
unions, enums, and typedefs" in Documentation/kernel-doc-nano-HOWTO.txt.
 
> BTW, what is @size? there's no size field in kexec_buf. I think it is not
> necessary to add these comment, they are easy to understand. If you really
> want, please rewrite them correctly, for example "image" description is
> wrong. It is not only for searching memory only, top_down description is
> also bad.

Sorry, I moved these comments from kexec_locate_mem_hole but forgot to 
rename the parameters to what they are called in struct kexec_buf. @size 
should have been @memsz (other fields also have wrong names, I'll fix them 
as well). The image description is correct in the context of where struct 
kexec_buf is used and explains what it will be used for in the function 
taking kexec_buf as an argument. It is not meant as a general description of 
the purpose of struct kimage. What is bad about the description of top_down?

I decided to add these comments because struct kexec_buf is now part of the 
kernel API for kexec. kernel-doc-nano-HOWTO.txt says:

> We definitely need kernel-doc formatted documentation for functions
> that are exported to loadable modules using EXPORT_SYMBOL.
> 
> We also look to provide kernel-doc formatted documentation for
> functions externally visible to other kernel files (not marked
> "static").
> 
> We also recommend providing kernel-doc formatted documentation
> for private (file "static") routines, for consistency of kernel
> source code layout.  But this is lower priority and at the
> discretion of the MAINTAINER of that kernel source file.

If you think they are not necessary or just add clutter I can leave them 
out.

-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

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