| Message ID | 5025034.R6Ttz76WZM@hactar (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
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 > > > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec > >
----- 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
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.
On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote: > 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. You are right and I was wrong! > > > 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? It is not clear enough to me, I personally think the original one in source code is better: /* allocate from top of memory hole */ > > 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. I'm fine with either way. THanks Dave
Am Dienstag, 28 Juni 2016, 00:19:48 schrieb Dave Young: > On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote: > > Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young: > > What is bad about the description of top_down? > It is not clear enough to me, I personally think the original one in > source code is better: > /* allocate from top of memory hole */ Actually I realized there's some discrepancy in how the x86 code uses top_down and how I need it to work in powerpc. This may be what is confusing about my comment and the existing comment. x86 always walks memory from bottom to top but if top_down is true, in each memory region it will allocate the memory hole in the highest address within that region. I don't know why it is done that way, though. On powerpc, the memory walk itself should be from top to bottom, as well as the memory hole allocation within each memory region. Should I add a separate top_down argument to kexec_locate_mem_hole to control if the memory walk should be from top to bottom, and then the bottom_up member of struct kexec_buf controls where inside each memory region the memory hole will be allocated?
Am Montag, 27 Juni 2016, 13:37:58 schrieb Thiago Jung Bauermann: > Should I add a separate top_down argument to kexec_locate_mem_hole to > control if the memory walk should be from top to bottom, and then the > bottom_up member of struct kexec_buf controls where inside each memory > region the memory hole will be allocated? Er, "...the bottom_up member of struct kexec_buf..." should read "...the top_down member of struct kexec buf...".
Please ignore previous reply, I mistakenly send a broken mail without subject, sorry about it. Resend the reply here. On 06/27/16 at 01:37pm, Thiago Jung Bauermann wrote: > Am Dienstag, 28 Juni 2016, 00:19:48 schrieb Dave Young: > > On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote: > > > Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young: > > > What is bad about the description of top_down? > > It is not clear enough to me, I personally think the original one in > > source code is better: > > /* allocate from top of memory hole */ > > Actually I realized there's some discrepancy in how the x86 code uses > top_down and how I need it to work in powerpc. This may be what is confusing > about my comment and the existing comment. > > x86 always walks memory from bottom to top but if top_down is true, in each > memory region it will allocate the memory hole in the highest address within > that region. I don't know why it is done that way, though. I think we did not meaning to do this, considering kdump we have only one crashkernel region for searching (crashk_res) so it is fine. For kexec maybe changing the walking function to accept top_down is reasonable. Ccing Vivek see if he can remember something.. > > On powerpc, the memory walk itself should be from top to bottom, as well as > the memory hole allocation within each memory region. > > Should I add a separate top_down argument to kexec_locate_mem_hole to > control if the memory walk should be from top to bottom, and then the > bottom_up member of struct kexec_buf controls where inside each memory > region the memory hole will be allocated? > > -- > []'s > Thiago Jung Bauermann > IBM Linux Technology Center >
On 06/27/16 at 04:21pm, Dave Young wrote: > Please ignore previous reply, I mistakenly send a broken mail without > subject, sorry about it. Resend the reply here. > > On 06/27/16 at 01:37pm, Thiago Jung Bauermann wrote: > > Am Dienstag, 28 Juni 2016, 00:19:48 schrieb Dave Young: > > > On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote: > > > > Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young: > > > > What is bad about the description of top_down? > > > It is not clear enough to me, I personally think the original one in > > > source code is better: > > > /* allocate from top of memory hole */ > > > > Actually I realized there's some discrepancy in how the x86 code uses > > top_down and how I need it to work in powerpc. This may be what is confusing > > about my comment and the existing comment. > > > > x86 always walks memory from bottom to top but if top_down is true, in each > > memory region it will allocate the memory hole in the highest address within > > that region. I don't know why it is done that way, though. > > I think we did not meaning to do this, considering kdump we have only > one crashkernel region for searching (crashk_res) so it is fine. > For kexec maybe changing the walking function to accept top_down is > reasonable. > > Ccing Vivek see if he can remember something.. > > > > > On powerpc, the memory walk itself should be from top to bottom, as well as > > the memory hole allocation within each memory region. What is the particular reason in powerpc for a mandatory top to bottom walking? > > > > Should I add a separate top_down argument to kexec_locate_mem_hole to > > control if the memory walk should be from top to bottom, and then the > > bottom_up member of struct kexec_buf controls where inside each memory > > region the memory hole will be allocated? Using one argument for both sounds more reasonable than using a separate argument for memory walk.. Thanks Dave
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];