Messages in this thread | | | Date | Wed, 3 Sep 2008 09:23:08 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH 4/9] Introduce container dump function |
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Quoting Andrey Mirkin (major@openvz.org): > Actually right now we are going to dump only one process. > Function for dumping head of image file are added. > > Signed-off-by: Andrey Mirkin <major@openvz.org> > --- > cpt/Makefile | 2 +- > cpt/checkpoint.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > cpt/cpt.h | 3 ++ > cpt/sys.c | 3 +- > kernel/fork.c | 2 + > 5 files changed, 82 insertions(+), 2 deletions(-) > create mode 100644 cpt/checkpoint.c > > diff --git a/cpt/Makefile b/cpt/Makefile > index bfe75d5..173346b 100644 > --- a/cpt/Makefile > +++ b/cpt/Makefile > @@ -2,4 +2,4 @@ obj-y += sys_core.o > > obj-$(CONFIG_CHECKPOINT) += cptrst.o > > -cptrst-objs := sys.o > +cptrst-objs := sys.o checkpoint.o > diff --git a/cpt/checkpoint.c b/cpt/checkpoint.c > new file mode 100644 > index 0000000..b4d9686 > --- /dev/null > +++ b/cpt/checkpoint.c > @@ -0,0 +1,74 @@ > +/* > + * Copyright (C) 2008 Parallels, Inc. > + * > + * Author: Andrey Mirkin <major@openvz.org> > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License as > + * published by the Free Software Foundation, version 2 of the > + * License. > + * > + */ > + > +#include <linux/sched.h> > +#include <linux/fs.h> > +#include <linux/file.h> > +#include <linux/version.h> > + > +#include "cpt.h" > + > +static int cpt_write_head(struct cpt_context *ctx) > +{ > + struct cpt_head hdr; > + > + memset(&hdr, 0, sizeof(hdr)); > + hdr.cpt_signature[0] = CPT_SIGNATURE0; > + hdr.cpt_signature[1] = CPT_SIGNATURE1; > + hdr.cpt_signature[2] = CPT_SIGNATURE2; > + hdr.cpt_signature[3] = CPT_SIGNATURE3; > + hdr.cpt_hdrlen = sizeof(hdr); > + hdr.cpt_image_major = (LINUX_VERSION_CODE >> 16) & 0xff; > + hdr.cpt_image_minor = (LINUX_VERSION_CODE >> 8) & 0xff; > + hdr.cpt_image_sublevel = (LINUX_VERSION_CODE) & 0xff; > + hdr.cpt_image_extra = 0; > +#if defined(CONFIG_X86_32) > + hdr.cpt_arch = CPT_ARCH_I386; > +#else > +#error Arch is not supported > +#endif > + return ctx->write(&hdr, sizeof(hdr), ctx); > +} > + > +int dump_container(struct cpt_context *ctx) > +{ > + int err; > + struct task_struct *root; > + > + read_lock(&tasklist_lock); > + root = find_task_by_vpid(ctx->pid); > + if (root) > + get_task_struct(root); > + read_unlock(&tasklist_lock); > + > + err = -ESRCH; > + if (!root) { > + eprintk("can not find root task\n"); > + return err; > + } > + ctx->nsproxy = root->nsproxy; > + if (!ctx->nsproxy) { > + eprintk("nsproxy is null\n"); > + goto out; > + }
The get_task_struct() above won't pin the tsk->nsproxy though, will it? So should you be doing a rcu_read_lock(); nsproxy = get_task_nsproxy(root); rcu_read_unlock(); to make sure the nsproxy doesn't disappear out from under you?
(Maybe you do it in a later patch...)
thanks, -serge
> + err = cpt_write_head(ctx); > + > + /* Dump task here */ > + if (!err) > + err = -ENOSYS; > + > +out: > + ctx->nsproxy = NULL; > + put_task_struct(root); > + return err; > +} > diff --git a/cpt/cpt.h b/cpt/cpt.h > index 607ac1b..b421a11 100644 > --- a/cpt/cpt.h > +++ b/cpt/cpt.h > @@ -33,6 +33,7 @@ typedef struct cpt_context > int refcount; > int ctx_state; > struct semaphore main_sem; > + struct nsproxy *nsproxy; > > int errno; > > @@ -54,3 +55,5 @@ extern int debug_level; > > #define eprintk(a...) cpt_printk(1, "CPT ERR: " a) > #define dprintk(a...) cpt_printk(1, "CPT DBG: " a) > + > +int dump_container(struct cpt_context *ctx); > diff --git a/cpt/sys.c b/cpt/sys.c > index 8334c4c..6801c22 100644 > --- a/cpt/sys.c > +++ b/cpt/sys.c > @@ -109,9 +109,10 @@ static int checkpoint(pid_t pid, int fd, unsigned long flags) > > ctx->file = file; > ctx->ctx_state = CPT_CTX_DUMPING; > + ctx->pid = pid; > > /* checkpoint */ > - err = -ENOSYS; > + err = dump_container(ctx); > > context_put(ctx); > > diff --git a/kernel/fork.c b/kernel/fork.c > index 52b5037..f38b43d 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -77,6 +77,7 @@ int max_threads; /* tunable limit on nr_threads */ > DEFINE_PER_CPU(unsigned long, process_counts) = 0; > > __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ > +EXPORT_SYMBOL(tasklist_lock); > > int nr_processes(void) > { > @@ -153,6 +154,7 @@ void __put_task_struct(struct task_struct *tsk) > if (!profile_handoff_task(tsk)) > free_task(tsk); > } > +EXPORT_SYMBOL(__put_task_struct); > > /* > * macro override instead of weak attribute alias, to workaround > -- > 1.5.6 > > _______________________________________________ > Containers mailing list > Containers@lists.linux-foundation.org > https://lists.linux-foundation.org/mailman/listinfo/containers
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