Quoting Sukadev Bhattiprolu (sukadev@xxxxxxxxxxxxxxxxxx): > (Trimmed Cc to Containers list). > > Updated patch to ignore ->child_stack_size on architectures that don't > need it. > > --- > >From e1e9b0b6eb511058961c1fb526f44b597790bfd7 Mon Sep 17 00:00:00 2001 > From: Sukadev Bhattiprolu <suka@suka.(none)> > Date: Tue, 20 Oct 2009 22:04:57 -0700 > Subject: [v13][PATCH 8/9] Define eclone() syscall > > Container restart requires that a task have the same pid it had when it was > checkpointed. When containers are nested the tasks within the containers > exist in multiple pid namespaces and hence have multiple pids to specify > during restart. > > eclone(), intended for use during restart, is the same as > clone(), except that it takes a 'pids' paramter. This parameter lets > caller choose specific pid numbers for the child process, in the > process's active and ancestor pid namespaces. (Descendant pid namespaces > in general don't matter since processes don't have pids in them anyway, > but see comments in copy_target_pids() regarding CLONE_NEWPID). > > eclone() also attempts to address a second limitation of the > clone() system call. clone() is restricted to 32 clone flags and all but > one of these are in use. If more new clone flags are needed, we will be > forced to define a new variant of the clone() system call. To address > this, eclone() allows at least 64 clone flags with some room > for more if necessary. > > To prevent unprivileged processes from misusing this interface, > eclone() currently needs CAP_SYS_ADMIN, when the 'pids' parameter > is non-NULL. > > See Documentation/eclone in next patch for more details and an > example of its usage. > > NOTE: > - System calls are restricted to 6 parameters and the number and sizes > of parameters needed for eclone() exceed 6 integers. The new > prototype works around this restriction while providing some > flexibility if eclone() needs to be further extended in the > future. > TODO: > - We should convert clone-flags to 64-bit value in all architectures. > Its probably best to do that as a separate patchset since clone_flags > touches several functions and that patchset seems independent of this > new system call. > > Changelog[v13-rc1]: > - [Nathan Lynch, Serge Hallyn] Rename ->child_stack_base to > ->child_stack and ensure ->child_stack_size is 0 on architectures > that don't need it (see comments in types.h for details). > > Changelog[v12]: > - [Serge Hallyn] Ignore ->child_stack_size if ->child_stack_base > is NULL. > - [Oren Laadan, Serge Hallyn] Rename clone_with_pids() to eclone() > Changelog[v11]: > - [Dave Hansen] Move clone_args validation checks to arch-indpeendent > code. > - [Oren Laadan] Make args_size a parameter to system call and remove > it from 'struct clone_args' > > Changelog[v10]: > - Rename clone3() to clone_with_pids() > - [Linus Torvalds] Use PTREGSCALL() rather than the generic syscall > implementation > > Changelog[v9]: > - [Roland McGrath, H. Peter Anvin] To avoid confusion on 64-bit > architectures split the new clone-flags into 'low' and 'high' > words and pass in the 'lower' flags as the first argument. > This would maintain similarity of the clone3() with clone()/ > clone2(). Also has the side-effect of the name matching the > number of parameters :-) > - [Roland McGrath] Rename structure to 'clone_args' and add a > 'child_stack_size' field > > Changelog[v8] > - [Oren Laadan] parent_tid and child_tid fields in 'struct clone_arg' > must be 64-bit. > - clone2() is in use in IA64. Rename system call to clone3(). > > Changelog[v7]: > - [Peter Zijlstra, Arnd Bergmann] Rename system call to clone2() > and group parameters into a new 'struct clone_struct' object. > > Changelog[v6]: > - (Nathan Lynch, Arnd Bergmann, H. Peter Anvin, Linus Torvalds) > Change 'pid_set.pids' to a 'pid_t pids[]' so size of 'struct pid_set' > is constant across architectures. > - (Nathan Lynch) Change pid_set.num_pids to unsigned and remove > 'unum_pids < 0' check. > > Changelog[v4]: > - (Oren Laadan) rename 'struct target_pid_set' to 'struct pid_set' > > Changelog[v3]: > - (Oren Laadan) Allow CLONE_NEWPID flag (by allocating an extra pid > in the target_pids[] list and setting it 0. See copy_target_pids()). > - (Oren Laadan) Specified target pids should apply only to youngest > pid-namespaces (see copy_target_pids()) > - (Matt Helsley) Update patch description. > > Changelog[v2]: > - Remove unnecessary printk and add a note to callers of > copy_target_pids() to free target_pids. > - (Serge Hallyn) Mention CAP_SYS_ADMIN restriction in patch description. > - (Oren Laadan) Add checks for 'num_pids < 0' (return -EINVAL) and > 'num_pids == 0' (fall back to normal clone()). > - Move arch-independent code (sanity checks and copy-in of target-pids) > into kernel/fork.c and simplify sys_clone_with_pids() > > Changelog[v1]: > - Fixed some compile errors (had fixed these errors earlier in my > git tree but had not refreshed patches before emailing them) > > Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx> Acked-by: Serge Hallyn <serue@xxxxxxxxxx> _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
