Commit 102f5aa4 authored by Chris Wilson's avatar Chris Wilson

drm/i915/gem: Serialise debugfs i915_gem_objects with ctx->mutex

Since the debugfs may peek into the GEM contexts as the corresponding
client/fd is being closed, we may try and follow a dangling pointer.
However, the context closure itself is serialised with the ctx->mutex,
so if we hold that mutex as we inspect the state coupled in the context,
we know the pointers within the context are stable and will remain valid
as we inspect their tables.
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: CQ Tang <cq.tang@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200723172119.17649-3-chris@chris-wilson.co.uk
parent 5ae26012
...@@ -326,6 +326,7 @@ static void print_context_stats(struct seq_file *m, ...@@ -326,6 +326,7 @@ static void print_context_stats(struct seq_file *m,
} }
i915_gem_context_unlock_engines(ctx); i915_gem_context_unlock_engines(ctx);
mutex_lock(&ctx->mutex);
if (!IS_ERR_OR_NULL(ctx->file_priv)) { if (!IS_ERR_OR_NULL(ctx->file_priv)) {
struct file_stats stats = { struct file_stats stats = {
.vm = rcu_access_pointer(ctx->vm), .vm = rcu_access_pointer(ctx->vm),
...@@ -346,6 +347,7 @@ static void print_context_stats(struct seq_file *m, ...@@ -346,6 +347,7 @@ static void print_context_stats(struct seq_file *m,
print_file_stats(m, name, stats); print_file_stats(m, name, stats);
} }
mutex_unlock(&ctx->mutex);
spin_lock(&i915->gem.contexts.lock); spin_lock(&i915->gem.contexts.lock);
list_safe_reset_next(ctx, cn, link); list_safe_reset_next(ctx, cn, link);
......
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